Vehicle Reverse Engineering Wiki

Bus Connections

The primary OBD-II connector on the driver's side hosts the following buses:

Data Pins Speed Connected To
Low-speed GMLAN 1 33.3K Coolant heater, HVAC, instrument cluster, keyless entry, seat heaters, onstar, radio, seat sensors, parking sensors, steering wheel multimedia buttons
Primary High speed GMLAN 6(+) 14(-) 500K onstar, parking brake, fuel pump, brakes, both drive motors, Engine control, HV drive electronics, AC compressor
Chassis high-speed GMLAN 12(+) 13(-) 500K brakes, both drive motors, Engine control, HV drive electronics, accelerometer, steering

Additionally, the second connector, located on the passenger's side, hosts the following:

Data pins Speed Connected To
Powertrain high-speed GMLAN 12(+) 13(-) 500K Both drive motors, Engine control, HV drive electronics, 12V inverter
High-voltage energy management high-speed GMLAN 3(+) 11(-) 500K HV battery charger, HV battery electronics

Finally, a 10.417 Kbit/s LIN bus is used to connect together the Body Control Module, window motors and switches, and the wiper motor. Another LIN bus appears to connect the HVAC controls back to the HVAC system.

Also see this page.

Volt Data

The volt is based on the GM Global A platform, but has some special modules installed and PIDs available specifically for the battery, charger, and motor electronics. These are documented in part below.

Live Data (Module-to-Module) from Primary High speed GMLAN

0C9 Byte 5 Accelerator 0 (0%) to 254 (100%)
0F1 Byte 2 Brake 0 (0%) to Unknown (254?) Typical pressure on brake pedal generates about 30.
120 Bytes 1-4 Odometer 1/64 km: e.g. 1234320 (0x0012D590) represents 19286.25 km or 11983.92 mi
135 Byte 1 Drive Position 0=Park, 1=Neutral, 2=Drive/L, 3=Reverse
1A1 Byte 7 Accelerator 0 (0%) to 254 (100%)
1C3 Byte 7 Accelerator 0 (0%) to 254 (100%) - This one includes automatic output from the cruise control
1EF Bytes 3-4 Gas Engine RPM RPM
1F5 Byte 4 Shift Position PRNDL 1=Park, 2=Reverse, N=Neutral, D=Drive, L=Low
206 Bytes 1-2 Battery SOC .250kWh Units possibly .244kWh
32A Bytes 1-4 GPS Latitude Milliarcseconds
32A Bytes 5-8 GPS Longitude Milliarcseconds
3E9 Bytes 1-2 Speed 1/64 KPH (90KPH would be 5760 (0x1580))
5EC Byte 3 Charging Current units 0.2 A (ex. 14.2 A = 0x47)
5EC Byte 4 Charging Voltage units 2 V (ex. 222V = 0x6F)
5EC Byte 5 Outside Air Temperature in °C unit 0.5°C offset +40 (exp.: 0x60 = 8.0 °C)
5EC Byte 6 Outside Air Temperature filtered in °C unit 0.5°C offset +40

Known PIDs (over ODB-II/UDS)

request over 7E4, answer in 5EC:
Onboard charger current: 0x4369
Onboard charger voltage: 0x4368
outside temperature (filtered): 0x801F
outside temperature (raw): 0x801E
High Voltage battery Temperature: 0x434F
Power Electronics Cooling Loop temperature: 0x1C43

Name ShortName Mode-PID # Equation Units
  1. of Bytes
Ambient Air Temp AAT 22-0046 X-40 °C 1
Control Module Voltage VPWR 22-0042 X*.001 V 2
Engine Coolant Temp ECT 22-0005 X-40 °C 1
Intake Manifold Absolute Pressure MAP 22-000B X+0 kPa 1
Engine RPM RPM 22-000C X*.25 rpm 2
Vehicle Speed Sensor VSS 22-000D X+0 kph 1
Ignition Timing Advance for #1 Cylinder SPARKADV 22-000E (X*.5)-64 BTDC 1
Intake Air Temperature IAT 22-000F X-40 °C 1
Commanded Throttle Actuator Control TAC 22-004C X*(100/255) % 1
Hybrid/EV Battery Pack Remaining Charge BAT_PWR 22-005B X*(100/255) % 1
Fuel System Status 22-1131 X+0 X+0
AC High Side Pressure 22-1564 Unknown kPa
Short Term Fuel Trim Bank 1 na 22-1570 X*(100/255) %
Short Term Fuel Trim Bank 2 na 22-1571 X*(100/255) %
Long Term Fuel Trim Bank 1 na 22-1572 X*(100/255) %
Long Term Fuel Trim Bank 2 na 22-1573 X*(100/255) %
Torque Delivered Signal na 22-1A2D Unknown NM
Output Shaft Speed na 22-1942 X*(1/4) or (1/8) RPM
Gear Ratio 22-19A1 na Might be X*(4/256) na
Trans Fluid Temp na 22-1940 X-40 °C
Transmission ISS na 22-1941 Might be X*(8192/65536) RPM


Chevy Volt Monitoring


Volt PIDs