Service Information

Volt

DTC P0AC4

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 P0AC4: Hybrid Powertrain Control Module Requested MIL Illumination

This DTC indicates the hybrid powertrain control module has set an emission related hybrid powertrain DTC. The hybrid powertrain control module sends a message via the serial data circuit to the engine control module (ECM) requesting illumination of the malfunction indicator lamp (MIL). When the ECM receives the message, DTC P0AC4 will set. The DTC information for the ECM will only display DTC P0AC4, but the freeze frame/failure records data may display the hybrid powertrain DTC that set.

Conditions for Running the DTC

•	Vehicle ON for greater than 3 s.

•	DTC P0AC4 runs continuously when the above condition is met.

Conditions for Setting the DTC

The hybrid powertrain control module has set an emission related DTC.

Action Taken When the DTC Sets

DTC P0AC4 is a Type A DTC.

Conditions for Clearing the DTC

DTC P0AC4 is a Type A DTC.

Reference Information

Description and Operation

Hybrid Modes of Operation Description

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Note: Correct any engine control DTCs before diagnosing hybrid powertrain control module DTCs.

DTC P0AC4 is an informational DTC. If there are no other engine control DTCs set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for diagnosis of hybrid powertrain control module DTCs.
Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.