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 P0A7E: Hybrid Battery Pack Overtemperature

Circuit/System Description

The engine control module (ECM) monitors the hybrid battery pack for an overtemperature condition.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

Maximum module temperature is greater than 57°C (134.6°F) for 1.7 minutes.

Action Taken When the DTC Sets

Does not affect hybrid system operation.

Conditions for Clearing the DTC

Hybrid battery temperature returns to lower than or equal to 57°C (134.6°F).

Diagnostic Aids

    • Possible battery pack cooling fan concern
    • Foreign material blocking vents

Reference Information

Schematic Reference

Hybrid Energy Storage Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Generator Battery Carrier Description and Operation

Electrical Information Reference

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

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Caution: To help avoid personal injury, additional precautions must be taken prior to working on the generator control module or the generator starter. After removing the 36V battery cables from the generator battery, remove both engine wiring harness connectors from the generator control module. Wait at least 5 minutes and then remove the generator control module cover. Verify voltage levels at all 36V, 12V, and 3-phase connections, are less than 3 volts using a DMM before proceeding.

Caution: To help avoid personal injury, be careful when working in the vicinity of the generator battery disconnect control module. Internal components will still be live, 36V potential, even when the cover has been opened or removed.

  1. With a scan tool, clear the DTC.
  2. Ignition OFF, wait 30 seconds.
  3. Ignition ON, operate the vehicle within the Conditions for Running the DTC and verify the DTC does not reset.
  4. If the DTC resets, replace the BECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for BECM replacement, setup, and programming