Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Hybrid Powertrain Control Module
LocationÂ
The hybrid powertrain control module is a non-serviceable, flash-programmable micro-processor contained within the power inverter module assembly.
Operating FunctionsÂ
The hybrid powertrain control module is the main controller of hybrid operation. The hybrid powertrain control module determines when to perform hybrid operation modes such as engine Auto-stop and regenerative braking. The hybrid powertrain control module also operates in conjunction with the battery energy control module to determine when to enable and disable the DC high voltage circuits. Each motor control module operates the applicable electric motor generator based upon hybrid powertrain control module commands.
Communication and Hosted DiagnosticsÂ
The hybrid powertrain control module is the host controller for diagnostic trouble code (DTC) information for the following control modules:
- Accessory DC power control module
- Battery energy control module
- Motor control module 1
- Motor control module 2
- Auxiliary transmission fluid pump control module
These modules diagnose their own operation and determine when a fault condition is present. Diagnostic status is communicated to the hybrid powertrain control module through the following circuits:
- accessory DC power control module utilizes the GM Hi-speed, Hybrid LAN communication circuit
- Battery energy control module utilizes the GM Hi-speed, Hybrid LAN communication circuit
- Each motor control module and the hybrid powertrain control module exchange information and commands on the SPI bus internal communication circuit as well as the hi-speed hybrid GMLAN communication circuit.
- Auxiliary transmission fluid pump control module utilizes a dedicated diagnostic status circuit
In the event a hosted module communicates a fault condition, the hybrid powertrain control module will determine if hybrid operation is effected and notify the vehicle operator by requesting the MIL illuminate and/or by displaying a hybrid service required message. In addition, the hybrid powertrain control module will store the associated DTC information for retrieval by a scan tool. Some hosted modules may require an ignition cycle to clear certain DTCs from the hybrid powertrain control module.
Circuit InputsÂ
In addition to GMLAN parameters, the hybrid powertrain control module directly monitors the following signal circuits:
- Transmission shift selector internal mode switch (IMS) Direction and Park/Neutral switch signals
- Engine crankshaft position (CKP) sensor signal
- Auxiliary transmission fluid pump diagnostic circuit
- High voltage interlock circuit (HVIC)
Circuit OutputsÂ
In addition to GMLAN and SPI bus commands, the hybrid powertrain control module directly controls the following output circuits:
- Auxiliary transmission fluid pump control circuit
- Battery energy control module high voltage contactor relay pulse width modulated (PWM) control circuit
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.