P0AC4

DTC P0AC4

Diagnostic Instructions

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

DTC Descriptor
DTC P0AC4
- Hybrid Powertrain Control Module Requested MIL Illumination

Circuit/System Description

The hybrid powertrain control module (HPCM) uses the GMLAN to signal the engine control module (ECM) that the hybrid system is requesting malfunction indicator lamp (MIL) illumination. This happens when the HPCM has determined that a failure affecting the hybrid system has occurred. When the ECM receives the message from the HPCM, DTC P0AC4 will set.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The HPCM is requesting MIL illumination.

Action Taken When the DTC Sets

DTC P0AC4 is a Type A DTC.

Conditions for Clearing the MIL/DTC

DTC P0AC4 is a Type A DTC.

Diagnostic Aids

DTC P0AC4 can not be cleared from the ECM until the related hybrid codes have been cleared.

Reference Information
DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Circuit/System Verification

1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to Hybrid Modes of Operation Description Hybrid Modes of Operation.
2. Ignition ON, verify the scan tool hood position parameter displays Open.

• If the hood position does not display Open, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle for DTC P254F.

Repair Instructions

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

Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle to correct any hybrid DTCs.