2017 Chevrolet Volt LT Hardware Modifications to allow Openpilot Operation - commaai/openpilot GitHub Wiki

Introduction

Several people have successfully enabled Openpilot operation on 2017 LT Volts without stock Premier features. This section will cover the hardware modifications required to enable Openpilot. Firmware modifications are required for OpenPilot.

Radar Module Installation (Optional, for LT and LKAS-Only Premier without Stock ACC Radar)

Parts Required

Tools Required

  • Torx #12 Screw Drivers - 8 screws on the top and 6 on splash shield in two wheels
  • 7mm socket and wrench - For 2x 7mm bolts on the two sides of bumper
  • Drills, drill bit, and 4mm rivet and riveters(or 2x 4mm or 8/32" (1/2" or 3/4" long) bolts and nuts) - for removing and installing 2 rivets holding upper grille to bumper
  • (Optional) Wiper arm puller, some knife or sharp tool - To access hood release cable hole and punch a hole through hood release cable plug

Introduction

In order for OpenPilot to work, at this time you must have a radar. (Vision-Only Longitudinal Control (VOACC) support in custom forks now makes radar optional). Since the LT does not have Adaptive Cruise Control, it does not have a radar, which means you have to install one. The stock mounting location for the radar is on the LT Volt, but the LT grille is not radar-compatible and the wiring harness is not installed. If you do not have a replacement grille, the old silver grille can be removed, leaving only a black base plate with a cutout for the radar. I ran my setup like this for several months without issue before I found a Premier Grille.

Bumper Removal

To install the radar the front bumper needs to be moved out of the way (only removing wheel-well and top bolts and tilting the bumper down). The LT grille also needs to be removed as it is not radar transparent. This is done by releasing a series of tabs that attach the silver grille to the black base plate.

There is a bolt inside the splash shield holding bumper and the car together. To remove it, try to pull out front end of splash shield, then use a 7mm hex wrench to unscrew the 7mm bolt. The space is small and you might need to turn the wheel all the way to left or right.

Put one hand into the splash shield, try push the middle of bumper plastic towards outside while pulling sturdy part of the bumper using another hand. You probably need to apply a little more force before unclipping it, avoid bending single point of plastic too hard, otherwise it could cause permanent deformation/crack.

You can also use wedge to unclip them. Carefully push a small nylon wedge between the fascia and the front fascia retainers. Insert a small flat-bladed tool into the fascia slot and depress the snaps one at a time and pull on the fascia at the same time to gradually remove the fascia from the front fascia retainers of the fender.

After two crisp unclicks, you can finally pull out the bumper. Pull out the bumper. The two ends of bumper (where the plastic clip end is) might get caught up during

As long as the bumper is pulled out far enough, it will fall to the ground due to gravity, and you should be all set.

If you want to test the radar without ACC grille, you can separately remove the chrome-plated plastic panel from non-ACC grille. Non-ACC grille also has a cut in the middle, allowing radar to work if chrome-plastic part is removed.

If you want to install ACC Grille, prepare to drill and install 2 rivets. Please use the proper eye protection when drilling and avoid metal chips from getting into other parts of the car.

  1. Drill and remove the 2 rivets from the front bumper, next to 8 screws you removed at the beginning.
  2. Release the upper grille from the bumper grille tabs. Pull the grille from the backside of the bumper. Many clips from the bumper hold two parts together, try not to break them. The limited operating space might make this more difficult. It might be easier if you have bumper removed entirely.
  3. Install 2x new 4mm Rivets (or 2x 4mm or 8/32 inch bolt (1/2" or 3/4" long) and nut (nylon anti-slip locked), use washers or wide head screw if possible)

Wiring

At this point we need to build a wire harness for the radar module since the LT Volt does not have this installed from the factory. I used 4 18 gauge wires because that’s what I had laying around, you could probably get away with using a smaller wire. I bundled the 4 wires together using electrical tape wrapped around the entire length of the harness (about 15 feet), you could use something else if desired (CAT7 Ethernet cable works nicely). I used a tap-a-circuit at the drivers side fuse panel to power the radar. Here they are listed for your reference:

  • Pin 6 - 12V ignition power for radar
  • Pin 7 - Ground
  • Pins 3, 5, 11 - Tied together, connect to OBDII Pin 3
  • Pins 2, 4, 10 - Tied together, connect to OBDII Pin 11

[!Warning] Solder and heat shrink/insulate the wires from the connector to the harness you made. Radar is safety-critical and exposed to weather, you should ensure the wiring connection is robust. Use hot glue, heat shrink, or other means to weatherproof connections.

Route the harness you made towards the drivers side following the factory harnesses, once up near the driver’s side corner of the engine compartment, find the hood release cable. In the driver’s side footwell you will see where it enters the engine compartment. I will say getting the wire into the cabin took a while for me, I ended up using a wire fish cable poked from inside the cabin to the engine compartment. It goes up and gets trapped in the vents under the windshield wipers. Then I attached the harness and pulled it into the cabin. This was by far the hardest part of this project.

3: hood release cable plug

Routing through firewall is the hardest part of this project. First you need to remove the wiper arm using wiper arm puller tool, then remove the air inlet grille panels under it. You only need to remove the bolts on the left side.

Then you need to get wire through the hole of hood release cable. This cable has a rubber grommet that isolates cabin (inside firewall) and engine compartment (outside firewall). This keeps rainwater, engine smell, and noise away. The space available to use tools from the engine side is limited.

Punch a hole in the hood release cable rubber plug, then route the radar wiring through it. Try not to displace the rubber plug from the hole or break the plug.

Notes

Radar Misalignment

Radar could detect itself is misaligned if it's not on the right orientation/position. This will clear its alignment calibrations and cause it to through Radar Unlearned error.

Currently, radar needs a car with ASCM module to relearn alignment.

If you don't want to buy another radar, NEVER power up the radar without properly installing it to the front of the car

Premier Steering Wheel Installation (For LT Only)

Parts Required

  • Clock Spring: 39136243
  • Steering Wheel: 23365557
  • Clock Spring Connector Pins (3): 13575867
  • BCM Connector Pins: 13582297

Introduction

The LT Volt does not have LKAS (Lane Keeping Assist System) or ACC (Adaptive Cruise Control)/Collision Warning Distance switches. The premier wheel does, and it also has a steering wheel heater! So how do we get this functionality on the LT? It’s a rather simple procedure. The wheel can be found for about $70 on ebay. You will also need a new clock spring that has the contacts required for these options. That, in addition to a few wire terminals and you have the full functionality of a Premier steering wheel. This modification is optional, as it has no real functionality on the stock fork of Openpilot. Certain forks, such as Twilsonco's, allow use of the LKAS and ACC switches to turn on and off Lateral control and change following distance. First, disconnect the 12V battery since you will be working with the airbag.

Wiring modifications for ACC switches

One wire is required to be added between the clock spring connector (Module X85, Connector X1, Pin 15) and the BCM (Module K9, Connector X3, Pin 8). The BCM is located under the shifter center console, on the floor. The connectors are towards the drivers side.

NOTE: The LKAS LED will never light up, but it will turn LKAS off and on if you have a compatible fork of openpilot.

Wiring modifications for Heated Steering Wheel

Two wires are required to be added at the clock spring connector (Module X85, Connector X1, Pins 8/21) for ignition power and ground. For ground I found a bare bolt behind the steering column, for power I tapped into the same ignition power tap-a-fuse of the radar.

LKAS Camera Bypass Plug (Only for LKAS-Only Premier without Stock ACC Radar)

Parts Required

  • LKAS Camera Connector: 12-pin Molex 34825 Female Connector digikey
  • Two wires (probably thinner than 20awg for ease of soldering)

Introduction

If your Premier has a stock LKAS camera but not ACC radar, you might only need minimal hardware modifications to use OpenPilot by relying on Vision-Only ACC (VOACC) and disconnecting stock camera. In any case, you need to make Firmware modifications to allow OpenPilot to control acceleration and braking of your car.

With flashed firmware, if you try to plug in Comma using OBD-II harness (the USB C one from comma.ai), you probably will get a Harness Relay Malfunction error at the end (assuming it's already running compatible forks). This is because the OpenPilot detects the stock LKAS camera is still active on one of CAN bus (code), which might interfere OP's normal operation. You will need to unplug the LKAS camera to make this go away.

However, there is a CAN bus routing through the LKAS camera, and unplugging the connector will cut off this CAN bus, disrupting many critical modules (BCM, ECM, PSCM, braking booster), raising engine light, and crippling your car. What we need to do is to bridge two pairs of CAN bus pins to resume normal operation of other modules.

Some materials came from ZoneOS Volt Guide

LKAS Camera Bypass Plug

The pinout of the LKAS camera is shown below. We need to connect one CAN_H to another CAN_H, CAN_L to another CAN_L.

camera-pinout

  1. Ready a Molex 34825 female connector, Use a soldering iron to carefully solder wires to connect two pairs of CAN buses, like in the picture shown below (The picture also has radar_enable soldered, you only need to deal with four CAN pins).

CAN_L_connection CAN_H_connection radar-plug

  1. Carefully inspect the continuity and robustness of the soldered wires, use hot glues or other means to solidly insulate and fix the pins.

[!Warning]
PLEASE ensure the connections are ROBUST and INSULATED. Broken (H-H, L-L) or shorted (H<->L) CAN connection WILL cause you to LOSE CONTROL of the car (power-steering, accelerator, engine, traction control, gear shifting), and potentially DEADLY INJURY.

I designed a 3D-printed case to protect the Molex connector model. Make one if you have a 3D printer.

  1. Plug the LKAS camera connector into the finished Bypass Plug, start the car, and confirm you can steer and move the car. OpenPilot should no longer complain Harness Relay Malfunction. The engine light might raise and that's expected because other modules had a brief lost of communication and stored a DTC into their memory.

  2. (Optional) Clear the DTC (Diagnosis Trouble Code) using GDS2 or other means. This will clear all lost of communication history DTC and unlit your engine light.