• Introduction
• Description of J1939 Messages
• Procedure for Interpreting Messages
• Interpretable J1939 Messages

In this page, we cover some of the basics of what a J1939 message is and how these messages can be used to decipher information on the current state of the trucks. In addition, this page provides a detailed description of each of the message attributes for the different J1939 message formats, as supplied in the J1939/71 standard.

J1939 is a set of standards used by heavy duty vehicles (e.g. trucks) to support the passing of vehicle information in a systemic fashion via onboard data acquisition and communication devices, most commonly a CAN Communication Card. For an in depth overview of this standard, we recommend you review this helpful introduction and overview. In the truck-code framework, J1939 messages are stored under a j1939_pdu_typ object. This object contains the following attributes:

• timestamp: A timestamp object with attributes for the hour, minute, second, and millisecond. This may be used
• priority: value between 0 and 7 where 0 is the highest priority
• pdu_format: 0 to 255, has to do with the PGN
• pdu_specific: depends on PDU format
• src_address: message origin
• num_bytes: number of trailing bytes describing the specific message.
• data_field[]: list of integer values representing the content bytes of the message (maximum 8 bytes).

All generic messages are provided from the CAN card in the form presented above and are later parsed to their message-specific format (as described in the next section). In to identify which format the message should adopt, the pdu_format and pdu_specific values are combined to form a unique Parameter Group Number, or PGN, value. All standard message formats supplied by the J1939 consist of a unique PGN values, a subset of which for the messages that are interpreted for the purposes of this framework can be found the "Interpretable J1939 Messages" section on this page.

J1939 bus messages are low-level messages that are encoded and packetized to stream through a communication network; hence not readily usable. In order to convert these messages into a format that is human interpretable, this framework supports the conversion and decoding of PDU messages of in the format described in the previous section to a more appropriate format as depicted in the J1939/71 standard. This is done by utilizing a series of J1939Interpreter classes (one for each interpretable J1939 message format described in the next section), which provide a means of systematically converting messages via the following three methods:

• convert: This is the main method. It takes a PDU message, converts the data into its message specific format as dictated by the J1939/71 standard, and places the data in an object designed for that message. The message-specific associated with all interpreters can be found in include/jbus/j1939_struct.h. For example, if the message is of type TURBO (or turbocharger), the object consists of attributes for the turbocharger speed and lube oil temperature. A pointer to the newly generated object is then returned by this methods for later used.
• import: This method is used to parse the string PDU messages that may be stored using logging into an object. This is mainly for post-processing purposes and in order to convert strings of data printed data back into their structured format.
• print: Prints the message to a file or stdout. This is used mostly for debugging purposes and to collect information from the trucks in real-time.

For simplicity of usage, all interpreters are stored in a hash table used to quickly access individual interpreters in a compact sense. This interpreter mapping mapping is collected as follows:

#include <map>
#include "jbus/j1939_interpreters.h"  // get_interpreters

<map, J1939Interpreter*> interpreters = get_interpreters()

Individual interpreters are access through the PGN value that is unique to each interpreter. For example, to use the interpreter mapping to interpret a TSC1 message, this is done as follows:

#include "jbus/j1939_struct.h"  // j1939_pdu_typ
#include "jbus/j1939_utils.h"  // TSC1

j1939_pdu_typ *pdu;  // a PDU message that has been identified to be TSC1 type
void *interpreted_message = interpreters[TSC1]->convert(pdu)

For examples of the J1939 interpreter being used, refer to the source files for translating PDU messages and reading J1939 messages from the CAN card.

Only a subset of the J1939 message are available within the truck-code framework. These messages are represented in the table below, with subsequent sections describing the constituents of each message and what specific values refer to.

* Parameter group number (PGN) values are expressed in terms of (PDU format, PSU specific).

Engine Override Control Mode (0-3):

The override control mode defines which sort of command is used:

• 00 Override disabled - Disable any existing control commanded by the source of this command.
• 01 Speed control - Govern speed to the included “desired speed” value.
• 10 Torque control - Control torque to the included “desired torque” value.
• 11 Speed/torque limit control - Limit speed and/or torque based on the included limit values. The speed limit governor is a droop governor where the speed limit value defines the speed at the maximum torque available during this operation.

Engine Requested Speed Control Conditions (0-3):

This mode tells the engine control system the governor characteristics that are desired during speed control. The four characteristics defined are:

• 00 Transient Optimized for driveline disengaged and non-lockup conditions
• 01 Stability Optimized for driveline disengaged and non-lockup conditions
• 10 Stability Optimized for driveline engaged and/or in lockup condition 1 (e.g., vehicle driveline)
• 11 Stability Optimized for driveline engaged and/or in lockup condition 2 (e.g., PTO driveline)

Override Control Mode Priority (0-3):

This field is used as an input to the engine or retarder to determine the priority of the Override Control Mode received in the Torque/Speed Control message (see PGN 0). The default is 11 (Low priority). It is not required to use the same priority during the entire override function. For example, the transmission can use priority 01 (High priority) during a shift, but can set the priority to 11 (Low priority) at the end of the shift to allow traction control to also interact with the torque limit of the engine.

The four priority levels defined are:

• 00 - Highest Priority: Used for situations that require immediate action by the receiving device in order to provide safe vehicle operation (i.e., braking systems). This level of priority should only be used in safety critical conditions.
• 01 - High Priority: Used for control situations that require prompt action in order to provide safe vehicle operation. An example is when the transmission is performing a shift and requires control of the engine in order to control driveline reengagement.
• 10 - Medium Priority : Used for powertrain control operations which are related to assuring that the vehicle is in a stable operating condition. An example is when the traction control system is commanding the engine in order to achieve traction stability.
• 11 - Low Priority: Used to indicate that the associated command desires powertrain control but is needed for function which improves the driver comfort which may be overridden by other devices. An example is cruise control or the non-critical part of a transmission shift to a new gear.

Engine Requested Speed/Speed Limit (0-8031.875 RPM):

Parameter provided to the engine from external sources in the torque/speed control message. This is the engine speed which the engine is expected to operate at if the speed control mode is active or the engine speed which the engine is not expected to exceed if the speed limit mode is active.

Engine Requested Torque/Torque Limit (-125 to 125%):

Parameter provided to the engine or retarder in the torque/speed control message for controlling or limiting the output torque.

Requested torque to the engine is measured in indicated torque as a percentage of reference engine torque (see the engine configuration message, PGN 65251). This is the engine torque at which the engine is expected to operate if the torque control mode is active or the engine torque which the engine is not expected to exceed if the torque limit mode is active.

Zero torque can be requested which implies zero fuel and, according to Figures SPN512_A and SPN512_B, the engine will not be allowed to stall. The actual engine percent torque (SPN 513) should be zero and the engine should decelerate until the low idle governor kicks in, at which time the actual engine percent torque will be calculated as shown in Figures SPN512_A and SPN512_B and the engine torque mode bits (SPN 899) should be equal to 0000b - Low Idle Governor.

Requested torque to the retarder is measured in indicated torque as a percentage of reference retarder torque (see the retarder configuration message, PGN 65249). The logic used in enabling or disabling the retarder is based on the override control mode priority bits (SPN 897).

A zero torque request to the retarder is a disable request, and is used by a J1939 node to prevent the retarder from being activated by other combinations of inputs outside of J1939 commands. The Torque Limit Mode is commonly used for this purpose.

Retarder Torque Mode (0-15):

State signal which indicates which retarder torque mode is currently generating, limiting, or controlling the torque. Note that the modes are not in prioritized order. Not all modes may be relevant for a given device. Some devices may not implement all functions. For typical priorities refer to Tables SPN518_A to SPN518_B for retarder control. The data type of this parameter is measured.

Mode 0000b means “No request”: retarder torque = 0 (no braking).

Modes 0001b to 1110b indicate that there is either a torque request or the identified function is currently controlling the retarder: retarder torque may range from 0 (no braking) to the upper limit.

Retarder Enable - Brake Assist Switch (0-15):

Switch signal which indicates whether the operator wishes the retarder to be enabled for vehicle braking assist. The retarder does not check this switch, nor does the enabling of this switch engage the retarder. When this switch is “enabled,” the devices constructing TSC1 – destination retarder messages may command retarder torque for braking. For example, the cruise control should not request retarder torque if this switch is not “enabled.” The switch exists to prevent the engine retarder from being asked to be engaged via TSC1 in a noise sensitive area. See also SPN 572

• 00 Retarder - brake assist disabled
• 01 Retarder - brake assist enabled
• 10 Error
• 11 Not available

Retarder Enable - Shift Assist Switch (0-3):

Switch signal which indicates whether the operator wishes the retarder to be enabled for transmission shift assist. The retarder does not check this switch, nor does the enabling of this switch engage the retarder. When this switch is “enabled,” the transmission may activate the retarder (via the TSC1 message) to increase the rate of engine deceleration to assist in shift control. The switch exists to prevent the engine retarder from being asked to be engaged via TSC1 in a noise sensitive area. See SPN 571.

• 00 Retarder - shift assist disabled
• 01 Retarder - shift assist enabled
• 10 Error
• 11 Not available

Actual Retarder - Percent Torque (-125 to 125%):

Actual braking torque of the retarder as a percent of retarder configuration reference torque SPN 556.

Intended Retarder Percent Torque (-125 to 125%):

Braking torque of retarder that the retarder is currently trying to achieve. This value takes into account all static limitations, but not the limitations due to the dynamic behavior of the retarder. This value, if unchanged over a certain time, can and will be reached by the actual retarder - percent torque (See SPN 520).

Engine Coolant Load Increase (0-3):

Status of an event, external to the engine, that may increase the nominal temperature of the engine coolant liquid.

• 00 - No coolant load increase
• 01 - Coolant load increase possible
• 10 - Error
• 11 - Not available

Retarder Requesting Brake Light (0-3):

Indicates that whether the retarder is requesting that the brake lights are illuminated.

• 00 - Retarder is not requesting that the brake lights are illuminated
• 01 - Retarder is requesting that the brake lights are illuminated
• 10 - Reserved
• 11 - Not available/Take no action

Retarder Road Speed Limit Switch (0-3):

Retarder road speed limit switch states:

• 00 - Road speed limiting by retarder is disabled
• 01 - Road speed limiting by retarder is enabled. The road speed that the retarder will limit will be determined when the switch transitions from 00 to 01
• 10 - Error Indicator
• 11 - Not Available

Retarder Road Speed Exceeded Status (0-3):

Retarder Road Speed Exceeded Status:

• 00 - Road speed is below threshold
• 01 - Road speed is above threshold and retarder is allowed to be activated
• 10 - Reserved
• 11 - Don't care/Take no action

Source Address of Controlling Device for Retarder Control (0-255):

The source address of the SAE J1939 device currently controlling the retarder. It is used to expand the torque mode parameter (see SPN 899) in cases where control is in response to an ECU that is not listed in Table SPN899_A. Its value may be the source address of the ECU transmitting the message (which means that no external SAE J1939 message is providing the active command) or the source address of the SAE J1939 ECU that is currently providing the active command in a TSC1 (see PGN 0) or similar message. Note that if this parameter value is the same as the source address of the device transmitting it, the control may be due to a message on a non-SAE J1939 data link such as SAE J1922 or a proprietary link.

Drivers Demand Retarder - Percent Torque (-125 to 125%):

The maximum torque selected by the driver when one or more modes are selected by the driver, such as hand lever, switch, constant torque, constant velocity, etc.

Retarder Selection, Non-Engine (0-100%):

The position of the driver’s selector for retarders that are not part of the engine system, expressed as percent and determined by the ratio of current position to the maximum possible position. The physical device may be a lever, rotary dial, combination of switches, or other device that the driver can use to select the type or amount of retardation needed.

Actual Maximum Available Retarder - Percent Torque (-125 to 125%):

This is the maximum amount of torque that the retarder can immediately deliver. It is the same as the maximum torque shown in the Retarder’s Configuration message, but allows for a much faster rate of change than could be communicated by reissuing the configuration message.

ASR Engine Control Active (0-3):

State signal which indicates that ASR engine control has been commanded to be active. Active means that ASR actually tries to control the engine. This state signal is independent of other control commands to the engine (e.g., from the transmission) which may have higher priority.

• 00 - ASR engine control passive but installed
• 01 - ASR engine control active
• 10 - Reserved
• 11 - Not available

ASR Brake Control Active (0-3):

State signal which indicates that ASR brake control is active. Active means that ASR actually controls wheel brake pressure at one or more wheels of the driven axle(s).

• 00 - ASR brake control passive but installed
• 01 - ASR brake control active
• 10 - Reserved
• 11 - Not available

Anti-Lock Braking (ABS) Active (0-3):

State signal which indicates that the ABS is active. The signal is set active when wheel brake pressure actually starts to be modulated by ABS and is reset to passive when all wheels are in a stable condition for a certain time. The signal can also be set active when driven wheels are in high slip (e.g., caused by retarder). Whenever the ABS system is not fully operational (due to a defect or during off-road ABS operation) , this signal is only valid for that part of the system that is still working. When ABS is switched off completely, the flag is set to passive regardless of the current wheel slip conditions.

• 00 - ABS passive but installed
• 01 - ABS active
• 10 - Reserved
• 11 - Not available

EBS Brake Switch (0-3):

Switch signal which indicates that the brake pedal is being pressed. The EBS brake switch is independent of the brake light switch and has no provisions for external connections.

• 00 - Brake pedal is not being pressed
• 01 - Brake pedal is being pressed
• 10 - Error
• 11 - Not available

Brake Pedal Position (0-100%):

Ratio of brake pedal position to maximum pedal position. Used for electric brake applications. 0% means no braking. Also when there are two brake pedals on the machine (Left Brake Pedal Position SPN 3033 and Right Brake Pedal Position SPN 3032) the maximum of the two should be transmitted for Brake Pedal Position.

ABS Off-Road Switch (0-3):

Switch signal which indicates the position of the ABS off-road switch.

• 00 - ABS off-road switch passive
• 01 - ABS off-road switch active
• 10 - Error
• 11 - Not available

ASR Off-road Switch (0-3):

Switch signal which indicates the position of the ASR off-road switch.

• 00 - ASR off-road switch passive
• 01 - ASR off-road switch active
• 10 - Error
• 11 - Not available

ASR "Hill Holder" Switch (0-3):

Switch signal which indicates the position of the ASR “hill holder” switch.

• 00 - ASR “hill holder” switch passive
• 01 - ASR “hill holder” switch active
• 10 - Error
• 11 - Not available

Traction Control Override Switch (0-3):

Switch signal which indicates the position of the traction control override switch. The traction control override signal disables the automatic traction control function allowing the wheels to spin.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not available or not installed

Accelerator Interlock Switch (0-3):

Switch signal used to disable the accelerator and remote accelerator inputs, causing the engine to return to idle.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not available

Engine Derate Switch (0-3):

Switch signal used to activate the torque limiting feature of the engine. The specific nature of torque limiting should be verified with the manufacturer.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not available

Engine Auxiliary Shutdown Switch (0-3):

Switch signal which requests that all engine fueling stop.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not available

Remote Accelerator Enable Switch (0-3):

Switch signal which indicates that the remote accelerator has been enabled and controls the engine.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not available

Note: The accelerator interlock switch (see SPN 972) must be disabled in order for the remote accelerator to perform engine control.

Engine Retarder Selection (0-100%):

The position of the operator controlled selector, expressed as a percentage and determined by the ratio of the current position of the selector to its maximum possible position. Zero percent means no braking torque is requested by the operator from the engine while 100% means maximum braking.

ABS Fully Operational (0-3):

Signal which indicates whether an ABS system is fully operational or whether its functionality is reduced by a defect or by an intended action (e.g., by activation of an ABS-off-road switch or during special diagnostic procedures). There are cases where the signal is necessary to fulfill legal regulations for special applications (e.g., switching off integrated retarders).

• 00 - Not Fully Operational
• 01 - Fully Operational
• 10 - Reserved
• 11 - Not available

EBS Red Warning Signal (0-3):

This parameter commands the EBS red optical warning signal

• 00 - Off
• 01 - On
• 10 - Reserved
• 11 - Take no action

ABS/EBS Amber Warning Signal (Powered Vehicle) (0-3):

This parameter commands the ABS/EBS amber/yellow optical warning signal

• 00 - Off
• 01 - On
• 10 - Reserved
• 11 - Take no action

ATC/ASR Information Signal (0-3):

This parameter commands the ATC/ASR driver information signal, for example a dash lamp.

• 00 - Off
• 01 - On
• 10 - Reserved
• 11 - Take no action

Source Address of Controlling Device for Brake Control (0-255):

The source address of the SAE J1939 device currently controlling the brake system. Its value may be the source address of the ECU transmitting the message (which means that no external SAE J1939 message is providing the active command) or the source address of the SAE J1939 ECU that is currently providing the active command in a TSC1 (see PGN 0) or similar message. Note that if this parameter value is the same as the source address of the device transmitting it, the control may be due to a message on a non-SAE J1939 data link such as SAE J1922 or a proprietary link.

Halt Brake Switch (0-3):

Switch signal which indicates the position of the halt brake switch.

• 00 - Halt brake switch passive
• 01 - Halt brake switch active
• 10 - Error
• 11 - Not available

Trailer ABS Status (0-3):

State signal which indicates that ABS in the trailer is actively controlling the brakes. A message is sent to the tractor from the trailer (i.e. by PLC). The receiving device in the tractor transfers this information to the J1939 network. At the beginning of power on the message is sent by the trailer to indicate if this status information is supported. Timeout of the trailer ABS active can be done by monitoring of the Trailer warning light information.

• 00 - Trailer ABS Status Information Available But Not Active
• 01 - Trailer ABS Active
• 10 - Reserved
• 11 - Trailer ABS Status Information Not Available or Parameter Not Supported

Tractor-Mounted Trailer ABS Warning Signal (0-3):

This parameter commands the tractor-mounted trailer ABS optical warning signal.

• 00 Off
• 01 On
• 10 Reserved
• 11 Take no action

Transmission Driveline Engaged (0-3):

Driveline engaged indicates the transmission controlled portion of the driveline is engaged sufficiently to allow a transfer of torque through the transmission. Driveline engaged is ACTIVE whenever the transmission is in gear and the clutch (if controlled by the transmission controller) is less than 100% clutch slip (clutch able to transfer torque). This parameter should be used in conjunction with the parameter “Shift in Process” (SPN 574). While a shift is in process, the receiver should not assume that the driveline is either fully engaged or disengaged (i.e., cruise control).

• 00 - Driveline disengaged
• 01 - Driveline engaged
• 10 - Error
• 11 - Not available

Transmission Torque Converter Lockup Engaged (0-3): State signal which indicates whether the torque converter lockup is engaged.

• 00 - Torque converter lockup disengaged
• 01 - Torque converter lockup engaged
• 10 - Error
• 11 - Not available

Transmission Shift In Process (0-3):

Indicates that the transmission is in process of shifting from the current gear to the selected gear. This state is generally ACTIVE during the entire time that the transmission controls the vehicle. This includes any transmission clutch control, all engine control sequences, pulling to transmission neutral, and engaging the destination gear (e.g., until it is no longer sending commands and/or limits to the engine). See also SPN 560. (See Figure SPN574_A)

• 00 - Shift is not in process
• 01 - Shift in process
• 10 - Error
• 11 - Not available

Transmission Output Shaft Speed (0-8031.875 RPM):

Calculated speed of the transmission output shaft.

Percent Clutch Slip (0-100%):

Parameter which represents the ratio of input shaft speed to current engine speed (in percent).

Engine Momentary Overspeed Enable (0-3):

Command signal used to indicate that the engine speed may be boosted up to the maximum engine overspeed value to accommodate transmission downshifts. The maximum time for overspeed is limited by the time defined in the engine configuration message (see PGN 65,251). The transmission module must command a “override disabled” state at least once before the engine will accept a subsequent request for overspeed.

• 00 - Momentary engine overspeed is disabled
• 01 - Momentary engine overspeed is enabled
• 10 - Reserved
• 11 - Take no action

Progressive Shift Disable (0-3):

Command signal used to indicate that progressive shifting by the engine should be disallowed.

• 00 - Progressive shift is not disabled
• 01 - Progressive shift is disabled
• 10 - Reserved
• 11 - Take no action

Transmission Input Shaft Speed (0-8031.875 RPM):

Rotational velocity of the primary shaft transferring power into the transmission. When a torque converter is present, it is the output of the torque converter.

Source Address of Controlling Device for Transmission Control (0-255):

The source address of the SAE J1939 device currently controlling the transmission. Its value may be the source address of the ECU transmitting the message (which means that no external SAE J1939 message is providing the active command) or the source address of the SAE J1939 ECU that is currently providing the active command in a TSC1 (see PGN 0) or similar message. Note that if this parameter value is the same as the source address of the device transmitting it, the control may be due to a message on a non-SAE J1939 data link such as SAE J1922 or a proprietary link.

Accelerator Pedal 1 Low Idle Switch (0-3):

Switch signal which indicates the state of the accelerator pedal 1 low idle switch. The low idle switch is defined in SAE Recommended Practice J1843.

• 00 - Accelerator pedal 1 not in low idle condition
• 01 - Accelerator pedal 1 in low idle condition
• 10 - Error
• 11 - Not available

Accelerator Pedal Kickdown Switch (0-3):

Switch signal which indicates whether the accelerator pedal kickdown switch is opened or closed. The kickdown switch is defined in SAE J1843.

• 00 - Kickdown passive
• 01 - Kickdown active
• 10 - Error
• 11 - Not available

Road Speed Limit Status (0-3):

Status (active or not active) of the system used to limit maximum vehicle velocity.

• 00 - Active
• 01 - Not Active
• 10 - Error
• 11 - Not available

Note: While somewhat inconsistent with other J1939 status parameters, the states defining 00 = active and 01 = inactive for Road Speed Limit Status are NOT typographical errors, and should be implemented as stated.

Accelerator Pedal 2 Low Idle Switch (0-3):

Switch signal which indicates the state of the accelerator pedal 2 low idle switch. The low idle switch is defined in SAE J1843.

• 00 - Accelerator pedal 2 not in low idle condition
• 01 - Accelerator pedal 2 in low idle condition
• 10 - Error
• 11 - Not available

Note: Also refer to SPN 558 Accelerator Pedal 1 Low Idle Switch and SPN 2971 Accelerator Pedal 3 Low Idle Switch.

Accelerator Pedal Position 1 (0-100%):

The ratio of actual position of the analog engine speed/torque request input device (such as an accelerator pedal or throttle lever) to the maximum position of the input device. This parameter is intended for the primary accelerator control in an application. If an application has only one accelerator control, use SPN 91.

For on-highway vehicles, this will typically be the operator’s accelerator pedal. Although it is used as an input to determine powertrain demand, it also provides anticipatory information to transmission and ASR algorithms about driver actions.

Engine Percent Load At Current Speed (0-250%):

The ratio of actual engine percent torque (indicated) to maximum indicated torque available at the current engine speed, clipped to zero torque during engine braking.

Remote Accelerator Pedal Position (0-100%):

The ratio of actual position of the remote analog engine speed/torque request input device (such as an accelerator pedal or throttle lever) to the maximum position of the input device.

For example, in on-highway vehicles this could be an accelerator control device that is external to the drivers cab or an accelerator that is controlled by a hand lever from the operators seat.

The Remote Accelerator Enable Switch is SPN 969. This parameter enables the remote accelerator operation.

Accelerator Pedal Position 2 (0-100%):

The ratio of actual position of the second analog engine speed/torque request input device (such as an accelerator pedal or throttle lever) to the maximum position of the input device. This parameter is intended for secondary accelerator control in an application. If an application has only one accelerator control, use SPN 91.

Vehicle Acceleration Rate Limit Status (0-3):

Status (active or not active) of the system used to limit maximum forward vehicle acceleration.

• 00 - Limit not active
• 01 - Limit active
• 10 - Reserved
• 11 - Not available

Note: The effects of emission control limits, such as engine exhaust smoke control, are specifically excluded; they are not considered to be part of a function to limit vehicle acceleration.

Actual Maximum Available Engine - Percent Torque (0-100%):

This is the maximum amount of torque that the engine can immediately deliver as a percentage of the reference engine torque (SPN 544). The Actual Maximum Available Engine - Percent Torque shall take into consideration all engine torque derates (e.g. air fuel ratio control (AFC), noise control, etc.) that could potentially be active in the system. This parameter differentiates itself from the engine percent torque points 1 through 5 of the engine configuration map because it takes into account all dynamic internal inputs such as AFC and that it is updated on a 50ms basis.

Engine Torque Mode (0-15):

State signal which indicates which engine torque mode is currently generating, limiting, or controlling the torque. Note that the modes are not in prioritized order. Not all modes may be relevant for a given device. Some devices may not implement all functions. For typical priorities refer to Figures SPN512_A and SPN512_B for engine control. The data type of this parameter is measured.

Mode 0000b means “No request”: engine torque may range from 0 to full load only due to low idle governor output.

Modes 0001b to 1110b indicate that there is either a torque request or the identified function is currently controlling the engine: engine torque may range from 0 (no fueling) to the upper limit.

Actual Engine - Percent Torque High Resolution (0-0.875%):

This parameter displays an additional torque in percent of the reference engine torque.

When the MSB is set to 1, this parameter is not available. When the MSB is set to 0, bits 1 to 3 indicate the desired torque with resolution of 0.125%/bit . Range is from 0 to 0.875% of reference torque.

The parameter is used in combination with SPN 513 Actual Engine Torque. The resulting actual engine torque will be calculated by adding these two parameters.

Driver's Demand Engine - Percent Torque (-125 to 125%):

The requested torque output of the engine by the driver. It is based on input from the following requestors external to the powertrain: operator (via the accelerator pedal), cruise control and/or road speed limit governor. Dynamic commands from internal powertrain functions such as smoke control, low- and high-speed engine governing; ASR and shift control are excluded from this calculation. The data is transmitted in indicated torque as a percent of the reference engine torque. See PGN 65251 for the engine configuration message. Several status bits are defined separately to indicate the request which is currently being honored. This parameter may be used for shift scheduling.

Actual Engine - Percent Torque (-125 to 125%):

The calculated output torque of the engine. The data is transmitted in indicated torque as a percent of reference engine torque (see the engine configuration message, PGN 65251). The engine percent torque value will not be less than zero and it includes the torque developed in the cylinders required to overcome friction.

Engine Speed (0-8031.875 RPM):

Actual engine speed which is calculated over a minimum crankshaft angle of 720 degrees divided by the number of cylinders.

Source Address of Controlling Device for Engine Control (0-255):

The source address of the SAE J1939 device currently controlling the engine. It is used to expand the torque mode parameter (see SPN 899) in cases where control is in response to an ECU that is not listed in Table SPN899_A. Its value may be the source address of the ECU transmitting the message (which means that no external SAE J1939 message is providing the active command) or the source address of the SAE J1939 ECU that is currently providing the active command in a TSC1 (see PGN 0) or similar message. Note that if this parameter value is the same as the source address of the device transmitting it, the control may be due to a message on a non-J1939 data link such as SAE J1922 or a proprietary link.

Engine Starter Mode (0-15):

There are several phases in a starting action and different reasons why a start cannot take place.

• 0000 - start not requested
• 0001 - starter active, gear not engaged
• 0010 - starter active, gear engaged
• 0011 - start finished; starter not active after having been actively engaged (after 50ms mode goes to 0000)
• 0100 - starter inhibited due to engine already running
• 0101 - starter inhibited due to engine not ready for start (preheating)
• 0110 - starter inhibited due to driveline engaged or other transmission inhibit
• 0111 - starter inhibited due to active immobilizer
• 1000 - starter inhibited due to starter over-temp
• 1001-1011 - Reserved
• 1100 - starter inhibited - reason unknown
• 1101 - error (legacy implementation only, use 1110)
• 1110 - error
• 1111 - not available

Engine Demand – Percent Torque (-125 to 125%):

The requested torque output of the engine by all dynamic internal inputs, including smoke control, noise control and low and high speed governing.

Transmission Selected Gear (-125 to 125): The gear that the transmission will attempt to achieve during the current shift if a shift is in progress, or the next shift if one is pending (i.e., waiting for torque reduction to initiate the shift).

Transmission Actual Gear Ratio (0-64.255):

The gear currently engaged in the transmission or the last gear engaged while the transmission is in the process of shifting to the new or selected gear. Transitions toward a destination gear will not be indicated. Once the selected gear has been engaged then Transmission Current Gear (SPN 525) will reflect that gear.

Transmission Requested Range (0-255 per byte):

Range selected by the operator. Characters may include P, Rx, Rx-1...R2, R1, R, Nx, Nx-1...N2, N1, N, D, D1, D2..., Dx, L, L1, L2..., Lx-1, 1, 2, 3,... If only one displayed character is required, the second character shall be used and the first character shall be a space (ASCII 32) or a control character (ASCII 0 to 31). If the first character is a control character, refer to the manufacturer’s application document for definition.

Transmission Current Range (0-255 per byte):

Range currently being commanded by the transmission control system. Characters may include P, Rx, Rx-1...R2, R1, R, Nx, Nx-1...N2, N1, N, D, D1, D2..., Dx, L, L1, L2..., Lx-1, 1, 2, 3,... If only one displayed character is required, the second character shall be used and the first character shall be a space (ASCII 32) or a control character (ASCII 0 to 31). If the first character is a control character, refer to the manufacturer’s application document for definition.

Engine Fuel Flow Rate 1 (0 to 6425.5 m^3/h):

The rate at which the fuel is flowing through a fuel valve.

Engine Fuel Flow Rate 2 (0 to 6425.5 m^3/h):

The rate at which the fuel is flowing through a fuel valve.

Engine Fuel Valve 1 Position (0-100%):

The position of a gaseous fuel valve that is metering the fuel flow to the engine. 0% indicates no fuel flow through valve and 100% means maximum fuel flow through valve.

Engine Fuel Valve 2 Position (0-100%):

The position of a gaseous fuel valve that is metering the fuel flow to the engine. 0% indicates no fuel flow through valve and 100% means maximum fuel flow through valve.

Engine Pre-filter Oil Pressure (0-1000 kPa):

Gage pressure of the engine oil before the oil reaches the oil filter.

Engine Exhaust Gas Pressure (-250 to 251.99 kPa):

Gage pressure of the exhaust gasses as measured at the turbine inlet of the turbocharger.

Engine Fuel Rack Position (0-100%):

Measured position of the engine fuel rack. A value of 0% rack represents no fueling and a value of 100% rack represents maximum fueling.

Engine Gas Mass Flow Rate 1 (0-3212.75 kg/h):

Gas mass flow rate delivered to an engine through its first fuel control system. See SPN 3467 for the second fuel control system.

Instantaneous Estimated Brake Power (0-32127.5 kW):

Estimate of the power developed by the engine.

Estimated Percent Fan Speed (0-100%):

Estimated fan speed as a ratio of the fan drive (current speed) to the fully engaged fan drive (maximum fan speed). A two state fan (off/on) will use 0% and 100% respectively. A three state fan (off/intermediate/on) will use 0%, 50% and 100% respectively. A variable speed fan will use 0% to 100%. Multiple fan systems will use 0 to 100% to indicate the percent cooling capacity being provided.

Note that the intermediate fan speed of a three state fan will vary with different fan drives, therefore 50% is being used to indicate that the intermediate speed is required from the fan drive.

Fan Drive State (0-15):

This parameter is used to indicate the current state or mode of operation by the fan drive.

• 0000 - Fan off: Used to indicate that the fan clutch is disengaged and the fan is inactive.
• 0001 - Engine system–General: Used to indicate that the fan is active due to an engine system not otherwise defined.
• 0010 - Excessive engine air temperature: Used to indicate that the fan is active due to high air temperature.
• 0011 - Excessive engine oil temperature: Used to indicate that the fan is active due to high oil temperature.
• 0100 - Excessive engine coolant temperature: Used to indicate that the fan is active due to high coolant temperature.
• 0101 - Excessive transmission oil temperature: Used to indicate fan is active due to excessive transmission oil temperature.
• 0110 - Excessive hydraulic oil temperature: Used to indicate fan is active due to excessive hydraulic oil temperature.
• 0111 - Default Operation: Used to indicate fan is active due to a error condition resulting in default operation.
• 1000 - Not defined
• 1001 - Manual control: Used to indicate that the fan is active as requested by the operator.
• 1010 - Transmission retarder: Used to indicate that the fan is active as required by the transmission retarder.
• 1011 - A/C system: Used to indicate that the fan is active as required by the air conditioning system.
• 1100 - Timer: Used to indicate that the fan is active as required by a timing function.
• 1101 - Engine brake: Used to indicate that the fan is active as required to assist engine braking.
• 1110 - Other
• 1111 - Not available

Fan Speed (0-8031.875 RPM):

The speed of the fan associated with engine coolant system.

Hydraulic Fan Motor Pressure (0-32127.5 kPa):

The hydraulic pressure used to drive the fan system, sensed before the hydraulic fan motor.

Fan Drive Bypass Command Status (0-100%):

Status of the Fan Drive Bypass Command as being commanded by the ECU. The fan drive bypass diverts pump pressure away from the hydraulic motor to maintain the fan drive pressure. 0% is defined as no bypass (i.e. diverting no fan drive pressure) and 100% is defined as full bypass (i.e. diverting the maximum fan drive pressure) from the fan motor.

Front Axle Speed (0-250.996 km/h):

The average speed of the two front wheels.

Relative Speed; Front Axle, Left Wheel (-7.8125 to 7.8125 km/h):

The speed of the front axle, left wheel relative to the front axle speed, SPN 904.

Relative Speed; Front Axle, Right Wheel (-7.8125 to 7.8125 km/h):

The speed of the front axle, right wheel relative to the front axle speed, SPN 904.

Relative Speed; Rear Axle #1, Left Wheel (-7.8125 to 7.8125 km/h):

The speed of the rear axle #1, left wheel relative to the front axle speed, SPN 904.

Relative Speed; Rear Axle #1, Right Wheel (-7.8125 to 7.8125 km/h):

The speed of the rear axle #1, right wheel relative to the front axle speed, SPN 904.

Relative Speed; Rear Axle #2, Left Wheel (-7.8125 to 7.8125 km/h):

The speed of the rear axle #2, left wheel relative to the front axle speed, SPN 904.

Relative Speed; Rear Axle #2, Right Wheel (-7.8125 to 7.8125 km/h):

The speed of the rear axle #2, right wheel relative to the front axle speed, SPN 904.

High Resolution Total Vehicle Distance (0-21,055,406 km):

Accumulated distance traveled by the vehicle during its operation.

High Resolution Trip Distance (0-21,055,406 km):

Distance traveled during all or part of a journey.

Engine Turbocharger Lube Oil Pressure 1 (0-1000 kPa):

Gage pressure of oil in turbocharger lubrication system.

Engine Turbocharger 1 Speed (0-257,020 RPM):

Rotational velocity of rotor in the turbocharger.

Engine Turbocharger Oil Level Switch (0-3):

Switch signal which indicates the presence of oil at the turbocharger

• 00 - no oil present at turbocharger
• 01 - oil present at turbocharger
• 10 - error
• 11 - Not available

Nominal Friction - Percent Torque (-125 to 125%):

The calculated torque that indicates the amount of torque required by the basic engine itself added by the loss torque of accessories. It contains the frictional and thermodynamic loss of the engine itself, and the losses of fuel, oil and cooling pumps. The data is transmitted in indicated torque as a percent of reference engine torque (see the engine configuration message, PGN 65251).

The realization can be done by a map dependent on engine speed and engine temperature and an offset value for additional loss torques.

See SPN 2978 for an indicator that describes the possible inclusion of engine parasitic losses such as cooling fan, etc. in this parameter value.

Engine's Desired Operating Speed (0-8,031.875 RPM):

An indication by the engine of the optimal operating speed of the engine for the current existing conditions. These conditions may include the torque generated to accommodate powertrain demands from the operator (via the accelerator pedal), cruise control, road speed limit governors, or ASR. Dynamic commands from functions such as smoke control or shift control are excluded from this calculation.

Engine's Desired Operating Speed Asymmetry Adjustment (0-250):

This byte is utilized in transmission gear selection routines and indicates the engine's preference of lower versus higher engine speeds should its desired speed not be achievable. This is a scaled ratio such that 125 represents an equal preference for a speed lower or higher that the engine's indicated desired speed. The higher the asymmetry adjustment value is above 125, the more the engine prefers to be operated at or above its indicated desired speed. Conversely, the lower the asymmetry adjustment value is below 125, the more the engine prefers to operate at or below its indicated desired speed. Typically, the engine's asymmetry adjustment will be predicated on fuel consumption considerations, and under these conditions, the method for computing the asymmetry adjustment is indicated in Figure SPN519_A. The engine may include other factors into its asymmetry adjustment calculation such as temperatures, pressures, and other operating parameters.

Estimated Engine Parasitic Losses - Percent Torque (-125 to 125%):

The calculated torque that indicates the estimated amount of torque loss due to engine parasitics, such as cooling fan, air compressor, air conditioning, etc. It is expressed as a percent of Engine Reference Torque.

When the data value of this parameter is equal to FB it means that all parasitic losses calculated by the engine are included in the Engine's Nominal Friction Percent Torque (SPN 514).

Aftertreatment 1 Exhaust Gas Mass Flow (0-12851 kg/h per bit):

Measured/calculated exhaust gas mass upstream of the aftertreatment system in exhaust bank 1 and 2.

Aftertreatment 1 Intake Dew Point (0-3):

Indicates that the temperature on the intake side of the aftertreatment system has exceeded the dew point, as estimated by the ECM in exhaust bank 1.

• 00 - Not exceeded the dew point
• 01 - Exceeded the dew point
• 10 - Error
• 11 - Not available

Aftertreatment 1 Exhaust Dew Point (0-3):

Indicates that the temperature on the exhaust side of the aftertreatment has exceeded the dew point, as estimated by the ECM in exhaust bank 1.

• 00 - Not exceeded the dew point
• 01 - Exceeded the dew point
• 10 - Error
• 11 - Not available

Aftertreatment 2 Intake Dew Point (0-3):

Indicates that the temperature on the intake side of the aftertreatment system has exceeded the dew point, as estimated by the ECM in exhaust bank 2.

• 00 - Not exceeded the dew point
• 01 - Exceeded the dew point
• 10 - Error
• 11 - Not available

Aftertreatment 2 Exhaust Dew Point (0-3):

Indicates that the temperature on the exhaust side of the aftertreatment has exceeded the dew point, as estimated by the ECM in exhaust bank 2.

• 00 - Not exceeded the dew point
• 01 - Exceeded the dew point
• 10 - Error
• 11 - Not available

Trip Distance (0 to 526,385,151.9 km):

Distance traveled during all or part of a journey.

Total Vehicle Distance (0 to 526,385,151.9 km):

Accumulated distance traveled by vehicle during its operation.

Retarder Type (0-15):

A vehicle retarder is a supplementary device to the wheel brakes for the driver to better control the vehicle. The wheel brakes used in the vehicle are not designed for continuous retarding operation. In a prolonged period of braking, the brakes can be thermally over-stressed, causing the braking effect to be reduced or even lead to complete braking system failure. The vehicle retarder is designed for continuous operation for braking during downhill operation and is also used for braking the vehicle to comply with speed limits and traffic conditions.

This parameter provides some indication of the retarder dynamics. It is used in the retarder configuration message. The data type of this parameter is measured.

• 0000 - Electric/Magnetic
• 0001 - Hydraulic
• 0010 - Cooled Friction
• 0011 - Compression Release (Engine retarder)
• 0100 - Exhaust
• 0101-1101 - Not defined
• 1110 - Other
• 1111 - Not available

Retarder Location (0-15):

This parameter defines whether the “torque/speed curve” defined by the retarder configuration message (PGN 65249) is dependent on engine rpm, output shaft rpm, or other parameter. The data type of this parameter is measured.

• 0000 - (Primary) Engine Compression Release Brake (Engine rpm)
• 0001 - (Primary) Engine Exhaust Brake (Exhaust pressure)
• 0010 - (Primary) Transmission Input (Engine rpm)
• 0011 - (Secondary) Transmission Output (Output Shaft rpm)
• 0100 - (Secondary) Driveline (Output Shaft rpm)
• 0101 - Trailer (Vehicle speed)
• 0110-1101 - Not defined
• 1110 - Other
• 1111 - Not availables

Retarder Control Method (Retarder Configuration) (0-250 steps):

This parameter identifies the number of steps used by the retarder.

Retarder Speed At Idle, Point 1 (Retarder Configuration) (0-8,031.875 RPM):

Please reference PGN 65249.

Percent Torque At Idle, Point 1 (Retarder Configuration) (-125 to 125%):

The torque limit that indicates the available retarder torque which can be provided by the retarder at idle speed. The data is transmitted in indicated torque as a percent of the reference retarder torque.

Maximum Retarder Speed, Point 2 (Retarder Configuration) (0-8,031.875 RPM):

Maximum speed of retarder (Please reference PGN 65249).

Percent Torque At Maximum Speed, Point 2 (Retarder Configuration) (-125 to 125%):

The torque limit that indicates the available retarder torque which can be provided by the retarder at its maximum speed. Please reference PGN 65249. The data is transmitted in indicated torque as a percent of the reference retarder torque.

Retarder Speed At Point 3 (Retarder Configuration) (0-8,031.875 RPM):

Retarder speed of point 3 of the engine retarder torque map. Please reference PGN 65249.

Percent Torque At Point 3 (Retarder Configuration) (-125 to 125%):

The torque limit that indicates the available retarder torque which can be provided by the retarder at points 3 and 4 of the retarder torque map. Please reference PGN 65249. The data is transmitted in indicated torque as a percent of the reference retarder torque.

Retarder Speed At Point 4 (Retarder Configuration) (0-8,031.875 RPM):

Retarder speed of point 4 of the engine retarder torque map. Please reference PGN 65249.

Percent Torque At Point 4 (Retarder Configuration) (-125 to 125%):

The torque limit that indicates the available retarder torque which can be provided by the retarder at points 3 and 4 of the retarder torque map. Please reference PGN 65249. The data is transmitted in indicated torque as a percent of the reference retarder torque.

Retarder Speed At Peak Torque, Point 5 (Retarder Configuration) (0-8,031.875 RPM):

Please reference PGN 65249.

Reference Retarder Torque (Retarder Configuration) (0-64,255 Nm):

This parameter is the 100% reference value for all defined indicated retarder torque parameters. It is only defined once and doesn't change if a different retarder torque map becomes valid.

Percent Torque At Peak Torque, Point 5 (Retarder Configuration) (-125 to 125%):

The torque limit that indicates the available retarder torque which can be provided by the retarder at point 5 of the retarder torque map. Please reference PGN 65249. The data is transmitted in indicated torque as a percent of the reference retarder torque.

Engine Speed At Idle, Point 1 (Engine Configuration) (0-8,031.875 RPM):

Stationary low idle speed of engine which includes influences due to engine temperature (after power up) and other stationary changes (calibration offsets, sensor failures, etc). This parameter is point 1 of the engine configuration map (see PGN 65251).

Engine Percent Torque At Idle, Point 1 (Engine Configuration) (-125 to 125%):

The torque limit that indicates the available engine torque which can be provided by the engine at idle speed. This parameter may be influenced by engine temperature (after power up) and other stationary changes (calibration offsets, sensor failures, etc.) See also SPN 188. The data is transmitted in indicated torque as a percent of the reference engine torque.

Engine Speed At Point 2 (Engine Configuration) (0-8,031.875 RPM):

Engine speed of point 2 of the engine torque map (see PGN 65251 and supporting document). In engine configuration mode 1 and 3, point 2 is defined as the kick-in point from which torque is reduced to zero. In mode 2 (see Table PGN65251_A), there are no special requirements for the definition of this point.

Engine Percent Torque At Point 2 (Engine Configuration) (-125 to 125%):

The torque limit that indicates the available engine torque which can be provided by the engine at point 2 of the engine map (see PGN 65251 and supporting documents). In engine configuration mode 1 and 3 (see Table PGN65251_A see PGN 65251), point 2 is defined as the kick-in point from which torque is reduced to zero. In mode 2, there are no special requirements for the definition of this point. The data is transmitted in indicated torque as a percent of the reference engine torque.

Engine Speed At Point 3 (Engine Configuration) (0-8,031.875 RPM):

Engine speed of point 3, 4, and 5 of the engine torque map (see PGN 65251 and supporting document). It is recommended that one of these points indicate the peak torque point for the current engine torque map. Points 3, 4, and 5 are optional and lie between idle and point 2.

Engine Percent Torque At Point 3 (Engine Configuration) (-125 to 125%):

The torque limit that indicates the available engine torque which can be provided by the engine at point 3, 4, and 5 of the engine map (see PGN 65251 and supporting documents).. It is required that one of these points indicate the peak torque point for the current engine torque map. Points 3, 4, and 5 lie between idle and point 2. The data is transmitted in indicated torque as a percent of the reference engine torque.

Engine Speed At Point 4 (Engine Configuration) (0-8,031.875 RPM):

Engine speed of point 3, 4, and 5 of the engine torque map (see PGN 65251 and supporting document). It is recommended that one of these points indicate the peak torque point for the current engine torque map. Points 3, 4, and 5 are optional and lie between idle and point 2.

Engine Percent Torque At Point 4 (Engine Configuration) (-125 to 125%):

The torque limit that indicates the available engine torque which can be provided by the engine at point 3, 4, and 5 of the engine map (see PGN 65251 and supporting documents). It is required that one of these points indicate the peak torque point for the current engine torque map. Points 3, 4, and 5 lie between idle and point 2. The data is transmitted in indicated torque as a percent of the reference engine torque.

Engine Speed At Point 5 (Engine Configuration) (0-8,031.875 RPM):

Engine speed of point 3, 4, and 5 of the engine torque map (see PGN 65251 and supporting document). It is recommended that one of these points indicate the peak torque point for the current engine torque map. Points 3, 4, and 5 are optional and lie between idle and point 2.

Engine Percent Torque At Point 5 (Engine Configuration) (-125 to 125%):

The torque limit that indicates the available engine torque which can be provided by the engine at point 3, 4, and 5 of the engine map (see PGN 65251 and supporting documents). It is required that one of these points indicate the peak torque point for the current engine torque map. Points 3, 4, and 5 lie between idle and point 2. The data is transmitted in indicated torque as a percent of the reference engine torque.

Engine Speed At High Idle, Point 6 (Engine Configuration) (0-8,031.875 RPM):

Engine speed of high idle (point 6) of the engine torque map (see PGN 65251 and supporting document). In engine configuration mode 3 (see Figure PGN65251_C), point 6 is not defined by the engine torque map but by the governor characteristic and the zero torque line.

Engine Gain (Kp) Of The Endspeed Governor (Engine Configuration) (0-50.2 %/RPM):

The endspeed governor is defined as a linear line with the following equations (Capital letters mean physical values, small letters mean normalized values).

Engine Reference Torque (Engine Configuration) (0-64,255 Nm):

This parameter is the 100% reference value for all defined indicated engine torque parameters. It is only defined once and doesn't change if a different engine torque map becomes valid.

Engine Maximum Momentary Override Speed, Point 7 (Engine Configuration) (0-8,031.875 RPM):

The maximum engine speed above high idle allowed by the engine control during a momentary high idle override. This duration of the override is limited by the maximum momentary override time limit, SPN 534.

Engine Maximum Momentary Override Time Limit (Engine Configuration) (0-25 s):

The maximum time limit allowed to override the engine's high idle speed.

Engine Requested Speed Control Range Lower Limit (Engine Configuration) (0-2500 RPM):

The minimum engine speed that the engine will allow when operating in a speed control/limit mode.

Engine Requested Speed Control Range Upper Limit (Engine Configuration) (0-2500 RPM):

The maximum engine speed regardless of load that the engine will allow when operating in a speed control/limit mode, excluding any maximum momentary engine override speed, if supported.

Engine Requested Torque Control Range Lower Limit (Engine Configuration) (-125 to 125%):

The minimum engine torque that the engine will allow when operating in a torque control/limit mode.

Engine Requested Torque Control Range Upper Limit (Engine Configuration) (-125 to 125%):

The maximum engine torque that the engine will allow when operating in a torque control/limit mode.

Engine Extended Range Requested Speed Control Range Upper Limit (Engine configuration) (0-8,031.875 RPM):

The maximum engine speed regardless of load that the engine will allow when operating in a speed control/limit mode, excluding any maximum momentary engine override speed, if supported.

When the limit is higher than 2500 RPM the 'Requested Speed Control Range Upper Limit (Engine Configuration)' parameter (see SPN 536) will be transmitted with a value of 2500 RPM.

Engine Moment of Inertia (0-257.02 kg-m^2):

Moment of inertia for the engine, including items driven full-time by the engine such as fuel, oil and cooling pumps. The inertia from the following items are not included: flywheel, alternator, compressor, fan, and other engine-driven accessories.

Engine Default Torque Limit (0-64,255 Nm):

Companion parameter to Transmission Torque Limit (SPN 1845). This “echo” parameter provides confirmation to the transmission that the engine has received and will invoke the requested Transmission Torque Limit in the event that J1939 communication is lost between the two devices.

Support Variable Rate TSC1 Message (0-255):

This parameter indicates which TSC1 transmission rates are supported by the engine ECU in addition to the required 10ms transmission rate for temporary powertrain control purposes.

Where 0 = Transmission Rate Supported by Engine and 1 = Transmission Rate Not supported by Engine

Note: FF for this byte implies that the engine only supports standard temporary power train control (e.g. 10 ms)

Support TSC1 Control Purpose Group 1 (0-255):

This parameter indicates which TSC1 control purposes are supported in group 1 of 4. One bit is used to convey the support of each Control Purpose. A value of 0 equals supported and a value of 1 equals not supported. This bit logic is used to allow the default to FF to be backward compatible.

This group of 4 parameters (SPNs 3345, 3346, 3347, and 3348) indicates which TSC1 Control Purposes are supported by the engine ECU in addition to the Temporary Powertrain Control Purpose (which is denoted as control purpose P32). All ones in the Group 1 through 4 parameters indicates the engine only supports Temporary Powertrain Control.

Where 0 = Control Purpose is supported and 1 = Control Purpose is not supported

Support TSC1 Control Purpose Group 2 (0-255):

This parameter indicates which TSC1 control purposes are supported in group 2 of 4. One bit is used to convey the support of each Control Purpose. A value of 0 equals supported and a value of 1 equals not supported. This bit logic is used to allow the default to FF to be backward compatible.

This group of 4 parameters (SPNs 3345, 3346, 3347, and 3348) indicates which TSC1 Control Purposes are supported by the engine ECU in addition to the Temporary Powertrain Control Purpose (which is denoted as control purpose P32). All ones in the Group 1 through 4 parameters indicates the engine only supports Temporary Powertrain Control.

Where 0 = Control Purpose is supported and 1 = Control Purpose is not supported

Support TSC1 Control Purpose Group 3 (0-255):

This parameter indicates which TSC1 control purposes are supported in group 3 of 4. One bit is used to convey the support of each Control Purpose. A value of 0 equals supported and a value of 1 equals not supported. This bit logic is used to allow the default to FF to be backward compatible.

This group of 4 parameters (SPNs 3345, 3346, 3347, and 3348) indicates which TSC1 Control Purposes are supported by the engine ECU in addition to the Temporary Powertrain Control Purpose (which is denoted as control purpose P32). All ones in the Group 1 through 4 parameters indicates the engine only supports Temporary Powertrain Control.

Where 0 = Control Purpose is supported and 1 = Control Purpose is not supported

Support TSC1 Control Purpose Group 4 (0-255):

This parameter indicates which TSC1 control purposes are supported in group 4 of 4. One bit is used to convey the support of each Control Purpose. A value of 0 equals supported and a value of 1 equals not supported. This bit logic is used to allow the default to FF to be backward compatible.

This group of 4 parameters (SPNs 3345, 3346, 3347, and 3348) indicates which TSC1 Control Purposes are supported by the engine ECU in addition to the Temporary Powertrain Control Purpose (which is denoted as control purpose P32). All ones in the Group 1 through 4 parameters indicates the engine only supports Temporary Powertrain Control.

Where 0 = Control Purpose is supported and 1 = Control Purpose is not supported

Note: P32 is always supported and is Temporary Power Train Control (the original use of the TSC1 Command). The engine configuration will not indicate separate support of Temporary Power Train Control mode.

Engine Coolant Temperature (-40 to 210 deg C):

Temperature of liquid found in engine cooling system.

Engine Fuel Temperature 1 (-40 to 210 deg C):

Temperature of fuel (or gas) passing through the first fuel control system. See SPN 3468 for the second control system

Engine Oil Temperature 1 (-273 to 1735 deg C):

Temperature of the engine lubricant.

Engine Turbocharger Oil Temperature (-273 to 1735 deg C):

Temperature of the turbocharger lubricant.

Engine Intercooler Temperature (-40 to 210 deg C):

Temperature of liquid found in the intercooler located after the turbocharger.

Engine Intercooler Thermostat Opening (0-100%):

The current position of the thermostat used to regulate the temperature of the engine intercooler. A value of 0% represents the thermostat being completely closed and 100% represents the thermostat being completely open.

Power Takeoff Oil Temperature (-40 to 210 deg C):

Temperature of lubricant in device used to transmit engine power to auxiliary equipment.

Power Takeoff Speed (0-8031.875 RPM):

Rotational velocity of device used to transmit engine power to auxiliary equipment.

Power Takeoff Set Speed (0-8031.875 RPM):

Rotational velocity selected by operator for device used to transmit engine power to auxiliary equipment.

Engine PTO Governor Enable Switch (0-3):

Switch signal which indicates that the PTO governor toggle switch is in the enabled (ON) position and therefore it is possible to manage the PTO control function.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not available

Engine Remote PTO Governor Preprogrammed Speed Control Switch (0-3):

Switch signal which indicates that the remote PTO governor toggle switch is in the enabled (ON) position. If the toggle switch is enabled and other conditions are satisfied then the remote PTO governor feature is activated and the PTO governor will control at the preprogrammed speed.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not available

Engine Remote PTO Governor Variable Speed Control Switch (0-3):

Switch signal which indicates that the remote PTO governor toggle switch is in the enabled (ON) position. If the toggle switch is enabled and other conditions are satisfied then the remote PTO governor feature is activated and the PTO governor will control at a variable speed.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not available

Engine PTO Governor Set Switch (0-3):

Switch signal of the PTO control activator which indicates that the activator is in the position to "set" the engine PTO governor set speed.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not available

Engine PTO Governor Coast/Decelerate Switch (0-3):

Switch signal of the PTO control activator which indicates that the activator is in the position to "coast/decelerate" the PTO governor set speed.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not available

Engine PTO Governor Resume Switch (0-3):

Switch signal of the PTO control activator which indicates that the activator is in the position to "resume" a previously established PTO governor set speed.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not available

Engine PTO Governor Accelerate Switch (0-3):

Switch signal of the PTO control activator which indicates that the activator is in the position to "accelerate" the PTO governor set speed.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not available

Operator Engine PTO Governor Memory Select Switch (0-3):

Measured state of the operator’s engine PTO governor memory select switch. This switch selects which of the two available memory locations is to be used to store the dynamically assigned value. This speed will be set using the PTO governor set switch and modified using the PTO governor accelerate and coast/decelerate switches.

• 00 - PTO set speed memory 1 selected
• 01 - PTO set speed memory 2 selected
• 10 - error
• 11 - not available

Remote PTO Governor Preprogrammed Speed Control Switch #2 (0-3):

Switch signal which indicates that the remote PTO governor toggle switch #2 is in the enabled (ON) position. If the toggle switch is enabled and other conditions are satisfied then the remote PTO governor control feature is activated and the PTO governor will control at the preprogrammed speed #2.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not Available

Note: This switch is different than the 1-8 Preprogrammed Set Speeds because this is a physical switch input, not a user programmable set speed (although the associated PTO set speed for this toggle switch is user defined).

Auxiliary Input Ignore Switch (0-3):

Switch signal which overrides other switch input's ability to disable an engine's operating condition.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not Available

This switch input can be used to prevent the PTO from disengaging if another switch input's state changes. For example, if the PTO is normally disengaged when the clutch is depressed, then this switch would allow the user to use PTO while depressing the clutch.

Two Speed Axle Switch (0-3):

Switch signal which indicates the current axle range.

• 00 - Low speed range
• 01 - High speed range
• 10 - Error
• 11 - Not available

Parking Brake Switch (0-3):

Switch signal which indicates when the parking brake is set. In general the switch actuated by the operator's park brake control, whether a pedal, lever or other control mechanism. (See also SPN 619)

• 00 - Parking brake not set
• 01 - Parking brake set
• 10 - Error
• 11 - Not available

Cruise Control Pause Switch (0-3):

Switch signal which indicates the position of the Cruise Control Pause Switch used on Remote Cruise Control applications. The Cruise Control Pause Switch signal temporarily disables the Cruise Control function.

• 00 - Off
• 01 - On
• 10 - Error Indicator
• 11 -Take No Action

Park Brake Release Inhibit Request (0-3):

Park Brake Release Inhibit Request signals the desire that an applied park brake remain applied and limit the ability of the vehicle to be moved.

• 00 - Park Brake Release Inhibit not requested
• 01 - Park Brake Release Inhibit requested
• 10 - SAE reserved
• 11 - Unavailable

This parameter provides the capability to request the device controlling a parking brake to inhibit its release. This is intended for devices to request the park brake remain applied. Status 00b is provided when conditions recommending the application of the park brake no longer exist for the sender.

Wheel-Based Vehicle Speed (0-250.996 km/h):

Speed of the vehicle as calculated from wheel or tailshaft speed.

Cruise Control Active (0-3):

Cruise control is switched on. It is not ensured that the engine is controlled by cruise control, as in the case of a large driver's demand the engine is controlled by the driver while cruise control is active (maximum selection of cruise control and driver’s demand). The cruise control is set to 0 if a switch off condition occurs.

• 00 - Cruise control switched off
• 01 - Cruise control switched on
• 10 - Error
• 11 - Not available

Cruise Control Enable Switch (0-3):

Switch signal which indicates that it is possible to manage the cruise control function.

• 00 - Cruise control disabled
• 01 - Cruise control enabled
• 10 - Error
• 11 - Not available

Brake Switch (0-3):

Switch signal which indicates that the driver operated brake foot pedal is being pressed. This brake foot pedal is controlling the vehicles’ service brake (total vehicle braking application, not park brakes). It is necessary for safe drivetrain behavior that the switch activates before the physical braking components are activated (i.e. Disengage the cruise control function prior to the activation of friction brakes).

• 00 - Brake pedal released
• 01 - Brake pedal depressed
• 10 - Error
• 11 - Not Available

Clutch Switch (0-3):

Switch signal which indicates that the clutch pedal is being pressed. It is necessary for a safe drivetrain behavior that the clutch switch is set before the clutch is opened (cruise control function).

• 00 - Clutch pedal released
• 01 - Clutch pedal depressed
• 10 - Error
• 11 - Not available

Cruise Control Set Switch (0-3):

Switch signal of the cruise control activator which indicates that the activator is in the position “set.”

• 00 - Cruise control activator not in the position “set”
• 01 - Cruise control activator in position “set”
• 10 - Error
• 11 - Not available

Cruise Control Coast (Decelerate) Switch (0-3):

Switch signal of the cruise control activator which indicates that the activator is in the position “coast (decelerate).”

• 00 - Cruise control activator not in the position “coast”
• 01 - Cruise control activator in position “coast”
• 10 - Error
• 11 - Not available

Cruise Control Resume Switch (0-3):

Switch signal of the cruise control activator which indicates that the activator is in the position “resume.”

• 00 - Cruise control activator not in the position “resume”
• 01 - Cruise control activator in position “resume”
• 10 - Error
• 11 - Not available

Cruise Control Accelerate Switch (0-3):

Switch signal of the cruise control activator which indicates that the activator is in the position “accelerate.”

• 00 - Cruise control activator not in the position “accelerate”
• 01 - Cruise control activator in position “accelerate”
• 10 - Error
• 11 - Not available

Cruise Control Set Speed (0-250 km/h):

Value of set (chosen) velocity of velocity control system.

PTO Governor State (0-31):

This parameter is used to indicate the current state or mode of operation by the power takeoff (PTO) governor. In lieu of support for PTO Drive Engagement parameters, this parameter may represent the status of a PTO drive. The broadcasting device must ensure that each achieved state is conveyed in at least one message broadcast before a transition to another state is allowed.

• 00000 - Off/Disabled: Used to indicate that the PTO governor enable switch is in the off position.
• 00001 - Hold: Used to indicate that the PTO governor is active and currently maintaining a captured operating speed.
• 00010 - Remote Hold: Used to indicate that the remote PTO governor is active and the PTO governor is currently maintaining a captured operating speed.
• 00011 - Standby: Used to indicate that the PTO governor device enable switch is in the ON position and it is possible to manage the PTO governor.
• 00100 - Remote Standby: Used to indicate that the remote PTO governor device enable switch is in the ON position and it is possible to manage the PTO governor.
• 00101 - Set: Used to indicate that the PTO governor is establishing current speed as the operating speed (captured value).
• 00110 - Decelerate/Coast: Used to indicate that the PTO governor is in the process of ramping down, or coasting, from the current operating speed.
• 00111 - Resume: Used to indicate that the PTO governor is in the process of resuming the operating speed to a previously captured value.
• 01000 - Accelerate: Used to indicate that the PTO governor is in the process of ramping up the operating speed.
• 01001 - Accelerator Override: Used to indicate that the PTO governor is active but for the present time the engine is controlled by a large driver's demand.
• 01010 - Preprogrammed set speed 1: Used to indicate that the PTO device is establishing a first preprogrammed PTO governor set speed (user programmable) as the current operating speed.
• 01011 - Preprogrammed set speed 2: Used to indicate that the PTO device is establishing a second preprogrammed PTO governor set speed (user programmable) as the current operating speed.
• 01100 - Preprogrammed set speed 3: Used to indicate that the remote PTO device is establishing a third preprogrammed PTO governor set speed (user programmable) as the current operating speed.
• 01101 - Preprogrammed set speed 4: Used to indicate that the remote PTO device is establishing a fourth preprogrammed PTO governor set speed (user programmable) as the current operating speed.
• 01110 - Preprogrammed set speed 5: Used to indicate that the remote PTO device is establishing a fifth preprogrammed PTO governor set speed (user programmable) as the current operating speed.
• 01111 - Preprogrammed set speed 6: Used to indicate that the remote PTO device is establishing a sixth preprogrammed PTO governor set speed (user programmable) as the current operating speed.
• 10000 - Preprogrammed set speed 7: Used to indicate that the remote PTO device is establishing a seventh preprogrammed PTO governor set speed (user programmable) as the current operating speed.
• 10001 - Preprogrammed set speed 8: Used to indicate that the remote PTO device is establishing a eighth preprogrammed PTO governor set speed (user programmable) as the current operating speed.
• 10010 - PTO set speed memory 1: Used to indicate that PTO set speed memory one set state is active.
• 10011 - PTO set speed memory 2: Used to indicate that PTO set speed memory two set state is active.
• 10100-11110 - Not defined
• 11111 - Not available

Cruise Control States (0-7):

This parameter is used to indicate the current state, or mode, of operation by the cruise control device. This is a status parameter.

• 000 - Off/Disabled
• 001 - Hold
• 010 - Accelerate
• 011 - Decelerate
• 100 - Resume
• 101 - Set
• 110 - Accelerator Override
• 111 - Not available

Engine Idle Increment Switch (0-3):

Switch signal which indicates the position of the idle increment switch.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not available

Engine Idle Decrement Switch (0-3):

Switch signal which indicates the position of the idle decrement switch.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not available

Engine Test Mode Switch (0-3):

Switch signal which indicates the position of the engine test mode switch.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not available

Engine Shutdown Override Switch (0-3):

Switch signal which indicates the position of the engine shutdown override switch. This switch function allows the operator to override an impending engine shutdown.

• 00 - Off
• 01 - On
• 10 - Error
• 11 - Not available

Engine Fuel Rate (0-3,212.75 L/h):

Amount of fuel consumed by engine per unit of time.

Engine Instantaneous Fuel Economy (0-125.5 km/L):

Current fuel economy at current vehicle velocity.

Engine Average Fuel Economy (0-125.5 km/L):

Average of instantaneous fuel economy for that segment of vehicle operation of interest.

Engine Throttle Position (0-100%):

The position of the valve used to regulate the supply of a fluid, usually air or fuel/air mixture, to an engine. 0% represents no supply and 100% is full supply.

Engine Throttle 2 Position (0-100%):

The sensed position feedback of the valve, coming from a second electrical actuator for a second throttle plate, used to regulate the supply of a fluid, usually air or fuel//air mixture. 0% represents no supply and 100% is full supply. SPN 51 is used for the first throttle position feedback.

Barometric Pressure (0-125 kPa):

Absolute air pressure of the atmosphere.

Cab Interior Temperature (-273 to 1735 deg C):

Temperature of air inside the part of the vehicle that encloses the driver and vehicle operating controls.

Ambient Air Temperature(-273 to 1735 deg C):

Temperature of air surrounding vehicle.

Engine Air Inlet Temperature (-40 to 210 deg C):

Temperature of air entering vehicle air induction system.

Road Surface Temperature (-273 to 1735 deg C):

Indicated temperature of road surface over which vehicle is operating.

Engine Diesel Particulate Filter Inlet Pressure (0-125 kPa):

Exhaust back pressure as a result of particle accumulation on filter media placed in the exhaust stream.

Engine Intake Manifold #1 Pressure (0-500 kPa):

The gauge pressure measurement of the air intake manifold. If there are multiple air pressure sensors in the intake stream, this is the last one in flow direction before entering the combustion chamber. This should be the pressure used to drive gauges and displays.

Engine Intake Manifold 1 Temperature (-40 to 210 deg C):

Temperature of pre-combustion air found in intake manifold of engine air supply system.

Engine Air Inlet Pressure (0-500 kPa):

Absolute air pressure at inlet to intake manifold or air box.

Engine Air Filter 1 Differential Pressure (0-12.5 kPa):

Change in engine air system pressure, measured across the filter, due to the filter and any accumulation of solid foreign matter on or in the filter.

Engine Exhaust Gas Temperature (-273 to 1735 deg C):

Temperature of combustion byproducts leaving the engine.

Engine Coolant Filter Differential Pressure (0-125 kPa):

Change in coolant pressure, measured across the filter, due to the filter and any accumulation of solid or semisolid matter on or in the filter.

Alternator Current (0-250 A):

Measure of electrical current flow from the alternator. Alternator Current (High Range/Resolution) parameter SPN 1795 has a higher range and resolution of the same parameter.

Charging System Potential (Voltage) (0-3212.75 V):

Electrical potential measured at the charging system output. The charging system may be any device charging the batteries. This includes alternators, generators, solid state charger and other charging devices.

Battery Potential / Power Input 1 (0-3212.75 V):

This parameter measures the first source of battery potential as measured at the input of the ECM/actuator etc. coming from one or more batteries, irrespective of the distance between the component and the battery. This SPN is also used when ECM's are interconnected in a series configuration, where the source of power is coming directly or indirectly from the same battery/batteries.

Keyswitch Battery Potential (0-3212.75 V):

Battery potential measured at the input of the electronic control unit supplied through a keyswitch or similar switching device.

Clutch Pressure (0-4000 kPa):

Gage pressure of oil within a wet clutch.

Transmission Oil Level (0-100%):

Ratio of volume of transmission sump oil to recommended volume.

Transmission Filter Differential Pressure (0-500 kPa):

Change in transmission fluid pressure, measured after the filter, due to accumulation of solid or semisolid material on or in the filter.

Transmission Oil Pressure (0-4000 kPa):

Gage pressure of lubrication fluid in transmission, measured after pump.

Transmission Oil Temperature (-273 to 1735 deg C):

Temperature of the transmission lubricant.

Transmission Oil Level High / Low (-62.5 to 62.5 L):

Amount of current volume of transmission sump oil compared to recommended volume. Positive values indicate overfill. Zero means the transmission fluid is filled to the recommended level.

Transmission Oil Level Countdown Timer (0-15):

Once all vehicle conditions (such as vehicle stopped, etc) are met, some transmissions may require a ‘settling time’ to allow the fluid level to normalize. This parameter indicates how much of the required settling time remains. When time reaches 0, a valid oil level measurement value will be broadcast in SPN 3027 Transmission Oil Level High / Low.

• 0000 - less than 1 minute
• 0001 - One minute
• 0010 - Two minutes
• 0011 - Three minutes
• 0100 - Four minutes
• 0101 - Five minutes
• 0110 - Six minutes
• 0111 - Seven minutes
• 1000 - Eight minutes
• 1001 - Nine minutes
• 1010 - Ten minutes
• 1011 - Eleven minutes
• 1100 - Twelve minutes
• 1101 - Thirteen minutes
• 1110 - Error
• 1111 - Not Available

Transmission Oil Level Measurement Status (0-15):

Indicates if conditions are acceptable to obtain a valid transmission oil level measurement as conveyed in SPN 124 Transmission Oil Level or SPN 3027 Transmission Oil Level High / Low. If conditions are not acceptable, this parameter conveys to the operator what prevents conditions from being acceptable. Only one condition can be conveyed in this parameter at any given point in time. If multiple conditions exist, it is not important which condition is actually broadcast, as the driver must ‘correct’ each and every condition as it is presented before a valid oil level reading can be made. If multiple conditions exist that prevent a valid reading, the sender should broadcast one of those conditions until it is corrected; then the next condition can be conveyed to the operator, and so on.

• 0000 - Conditions valid for transmission oil level measurement
• 0001 - Conditions not valid – Settling timer still counting down
• 0010 - Conditions not valid – Transmission in gear
• 0011 - Conditions not valid – Transmission fluid temperature too low
• 0100 - Conditions not valid – Transmission fluid temperature too high
• 0101 - Conditions not valid – Vehicle moving; output shaft speed too high
• 0110 - Conditions not valid – Vehicle not level
• 0111 - Conditions not valid – Engine speed too low
• 1000 - Conditions not valid – Engine speed too high
• 1001 - Conditions not valid – No request for reading
• 1010 - Not defined
• 1011 - Not defined
• 1100 - Not defined
• 1101 - Conditions not valid - Other
• 1110 - Error
• 1111 - Not available

Hydraulic Retarder Pressure (0-4000 kPa):

Gage pressure of oil in hydraulic retarder system.

Hydraulic Retarder Oil Temperature (-40 to 210 deg C):

Temperature of oil found in a hydraulic retarder.