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 P0A1D: Hybrid Powertrain Control Module Internal Performance

Circuit/System Description

The drive motor generator power inverter control module (PIM) contains several microprocessors. This diagnostic applies to internal microprocessor integrity conditions within the hybrid powertrain control module (HPCM). The HPCM and each Motor Control Module (MCM) utilize a programmable logic device (PLD) to perform certain input and output functions. At ignition ON, the PLD expects to communicate with the HPCM and both MCMs. The PLD will communicate to MCM 1 over an internal communication circuit when it has established communications with the HPCM. MCM 1 will communicate to the engine control module (ECM) over GMLAN if the PLD has not established communication with the HPCM.

Conditions for Running the DTC

    • The control module runs the program to detect an internal fault when the key is ON.
    • Ignition voltage is 8-18 volts.

Conditions for Setting the DTC

The control module has detected an internal HPCM malfunction.

Action Taken When the DTC Sets

DTC P0A1D is a Type A DTC.

Conditions for Clearing the DTC

DTC P0A1D is a Type A DTC.

Diagnostic Aids

An intermittent loss of battery power to the drive motor generator power inverter module assembly (PIM) may set this DTC.

Reference Information

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Circuit/System Verification

  1. Clear the DTC information.
  2. Turn the ignition OFF for 1 minute.
  3. Turn the ignition ON.
  4. Retest for DTC P0A1D.

Circuit/System Testing

  1. Inspect for any communication U-code DTCs.
  2. If the specified DTCs are set, repair them first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
  3. Ignition OFF, disconnect the 12V battery. Refer to Battery Negative Cable Disconnection and Connection .
  4. Wait 2 minutes.
  5. Reconnect the 12V battery. Refer to Battery Negative Cable Disconnection and Connection .
  6. Ignition ON, retest for DTC P0A1D.
  7. If the DTC resets, program the PIM with the latest software version and recheck for DTCs. If the DTC resets after programming or if the PIM already contains the latest software version, replace the PIM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for PIM replacement, setup, and programming.