GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

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

DTC Descriptor

DTC P0C01: Drive Motor 1 Overcurrent

DTC P0C04: Drive Motor 2 Overcurrent

Circuit/System Description

The drive motor generator power inverter control module (PIM) contains two motor control modules (MCMs) and the hybrid powertrain control module (HPCM). Each MCM operates its respective drive motor generator based upon 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 drive motor generator operates utilizing 3-phase alternating current (ac) electricity. Each IGBT operates a single phase of the drive motor generator. Each phase is individually identified as U, V and W. Each MCM monitors the current of each phase in order to detect PIM overcurrent conditions.

Conditions for Running the DTC

The Hybrid Wakeup circuit is active.

Conditions for Setting the DTC

One or more phase currents are greater than 680 A.

Action Taken When the DTC Sets

    • DTCs P0C01 and P0C04 are Type A DTCs.
    • The PIM commands the battery energy control module (BECM) to open the high voltage contactor relays.

Conditions for Clearing the DTC

DTCs P0C01 and P0C04 are Type A DTCs.

Reference Information

Schematic Reference

Hybrid Controls Schematics

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Circuit/System Verification

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

Circuit/System Testing

    Danger: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.

    The High Voltage Disabling procedure will perform the following tasks:

       • Identify how to disable high voltage.
       • Identify how to test for the presence of high voltage.
       • Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.
    Failure to follow the procedures exactly as written may result in serious injury or death.

  1. Perform the High Voltage Disabling procedure for servicing at the drive motor generator control module cable connections.
  2. Remove the 3-phase cable assembly from the PIM distribution box. Refer to Generator Control Module 3-Phase Cable Assembly Replacement.
  3. Test the resistance to ground for each phase of the applicable drive motor generator by measuring between the following points with a DMM.
  4. • Phase U terminal and chassis ground
    • Phase V terminal and chassis ground
    • Phase W terminal and chassis ground
         ⇒If infinite resistance is measured, replace the PIM and retest for DTCs. If DTC P0C01 or P0C04 still resets, replace the 3-phase cable assembly and the drive motor generator assembly that corresponds to the set DTC.
         ⇒If less than infinite is measured, continue with Circuit/System Testing.
  5. Remove the 3-phase cable assembly from the transmission. Refer to Generator Control Module 3-Phase Cable Assembly Replacement. Ensure the terminals are not contacting chassis ground.
  6. Retest the resistance to ground for each phase of the 3-phase cable. Measure between the following points with a DMM.
  7. • Phase U terminal and chassis ground
    • Phase V terminal and chassis ground
    • Phase W terminal and chassis ground
    If infinite resistance is measured, replace the applicable drive motor generator.
    If less than infinite is measured, replace the generator control module 3-phase cable assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Control Module References for PIM replacement, setup, and programming.
    •  Generator Control Module 3-Phase Cable Assembly Replacement
    •  Drive Motor with Generator Assembly Removal - 1st Position
    •  Drive Motor with Generator Assembly Removal - 2nd Position