P0A79

DTC P0A78 or P0A79

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0A78
- Drive Motor 1 Inverter Performance

DTC P0A79
- Drive Motor 2 Inverter Performance

Circuit/System Description

The drive motor generator power inverter control module (PIM) contains two motor control modules (MCMs). Each MCM operates its respective drive motor generator based upon hybrid powertrain control module (HPCM) commands. Each MCM controls the speed, direction and output torque of its respective drive motor generator through the sequencing actuation of high current switching transistors called insulated gate bipolar transistors (IGBTs). Each IGBT assembly is monitored for fault conditions.

Conditions for Running the DTC

* The high voltage contactor relays are closed.
* Ignition voltage is 8-18 volts.

Conditions for Setting the DTC

The MCM detects excessive current flow through the switched portion of the IGBT.

Action Taken When the DTC Sets

* DTCs P0A78 and P0A79 are Type A DTCs.
* The PIM commands the battery energy control module (BECM) to open the high voltage relay contactors.

Conditions for Clearing the DTC

DTCs P0A78 and P0A79 are Type A DTCs.

Circuit/System Verification

1. Inspect for DTCs P1AF0 and P1AF2.

^ If the specified DTCs are set, repair them first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle. Diagnostic Trouble Code Descriptions

2. Clear the DTC information.
3. Turn the ignition OFF for 1 minute.
4. Turn the ignition ON.
5. Operate the vehicle within the conditions for running and setting.
6. Retest for the DTC.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Drive Motor Generator Power Inverter Module Cable Removal for 3 phase cable replacement.
* Drive Motor with Generator Assembly Removal - 1st Position for Drive Motor Generator 1 replacement.
* Drive Motor with Generator Assembly Removal - 2nd Position for Drive Motor Generator 2 replacement.