P0A8E

DTC P0A8E

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 Instructions) provides an overview of each diagnostic category.

DTC Descriptor
DTC P0A8E
- 14 Volt Power Module System Voltage High

Circuit/System Description

The Accessory Power Module (APM) continuously monitors its 14 volt circuit during charge or Jump Assist. This DTC sets when the 14 volt circuit in the APM rises above a set level. APM functions will run only when an APM enable message from the Hybrid Powertrain Control Module (HPCM) is active on the high speed hybrid GMLAN communication circuit.

Conditions for Running the DTC

APM is charging or in Jump Assist.

Conditions for Setting the DTC

* 14 volt circuit is above 16.5 volts while charging.
* 14 volt circuit is above 16.0 volts in Jump-Assist.

Action Taken When the DTC Sets

* DTC P0A8E is a Type C DTC.
* The APM will shutdown charging or Jump Assist.

Conditions for Clearing the DTC

* 14 volt circuit is below 16.3 volts while charging.
* 14 volt circuit is below 15.8 volts in Jump-Assist.

Diagnostic Aids

* A possible cause of this DTC could be overcharging with a battery charger or jump starting.
* A high voltage value in multiple modules indicates a concern in the charging system.

Reference Information
Schematic Reference

Hybrid Controls Schematics ()
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Drive Motor Generator Control Module Description and Operation ()
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

Verify with the scan tool that the BCM is reading the voltage correctly.

Circuit/System Testing

1. Turn the Ignition to ON.
2. Connect a DMM to the 14 volt battery.
3. Use the APM Low Voltage Control to turn on the APM 14 volt system. Vary the voltage setpoint with the scan tool ensuring that the DMM tracks the commanded voltage.

• If the Low Voltage Control fails, replace the APM.

Repair Instructions

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

Control Module References (Programming and Relearning) for APM replacement, setup, and programming.