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GM Terms

Also see general terms.

Term	Abbreviation	Definition
Advanced Safety Control Module	ASCM	Car computer/module that does sensor fusion from Radar and Camera to create ACC and LKA messages to PCM (powertrain control module). Typically located in the trunk.
Calibration	n/a	Packaged adjustments to running parameters of firmware running on GM vehicles. Updates available from SPS within TIS2Web
Firmware	n/a	Base operating system for various devices throughout the vehicle. Updates available from SPS within TIS2Web
GDS2	Global Diagnostic System 2	GM system for advanced diagnostics and firmware flashing
GMLAN	GM Local Area Network	Single wire propriety interface present on the CAN connector in GM vehicles.
MDI	Multiple Diagnostic Interface	GM service device connecting the vehicle to a computer. Lower price generics exist such as vxdiag.
SPS	Service Programming System	Firmware and calibrations within the TIS2Web application. Updates can be seen for vehicles by VIN without cost here.
Tech2Win	Tech2 for Windows	Emulated legacy diagnostic interfaces for Windows. Runs in an emulated terminal.
TIS2Web	Techline Information System	ACDelco site providing diagnostics and firmware for cars on a subscription basis. Interacts with vehicle via GM MDI. Java webstart application.

Vehicle Requirements

Most GM 2016-2020 vehicles with ACC, LKA.

Radar is behind flat Chevy logo:

ASCM in the trunk:

Unofficial Vehicles

Any GM vehicle 2016+ with front camera and LKA. These will only have ALC, not ACC. With a comma pedal, limited ACC is possible. See Unofficial GM fork for more info.

For the Chevy Bolt specifically, see the openpilot Bolt wiki.

Capabilities

Minimum Speeds

All: 8 mph for lateral control. First engagement must be above 18 mph.

2017: 8 mph for longitudinal control

2018+: 0 mph for longitudinal control

Auto-Resume

2017: Auto-resumes from stop at 0mph.

2018+: Must press RESUME to resume from stop.

Hardware

Recommended

1. comma two devkit w/ OBD-II car harness
2. ASCM wiring harness

Other ASCM Harness Methods

• Bypass ASCM and power the radar, choose one of:
  1. GM Giraffe - $300-$500
  2. ASCM connector Amazon / Amazon alt - $7-10 + Cam molex connector digikey - $10
  3. 0.1" header homebrew harness

Harness Examples

ASCM 14-pin stub

Camera stub

Connect switched +12V (e.g. ignition on, rearview mirror connector or driver fusebox) to pin 9 (radar power) of cam connector. This will turn on the front radar when the car is powered on.

Original instructions from Zoneos

Homebuilt ODB-II to ODB-C Harness

Map ODB-II to OBD-C female (at comma two) schematic May require the intercept relays in black and two pandas to be disabled:

• panda/board/main.c:
• Add case SAFETY_GM: fall-through after case SAFETY_ELM327:

	OBD-II		OBD-C
4	GND	GND
6	CAN1H	A2	CAN0H
14	CAN1L	A3	CAN0L
3	CAN2H	A11	CAN1H
11	CAN2L	A10	CAN1L
12	CAN3H	B2	CAN2H
13	CAN3L	B3	CAN2L
16	12V	VBUS
		B8	SBU2 1kΩ to GND