P0A8E

DTC P0A8E

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* 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 14 volt enable message active.

Conditions for Setting the DTC

* 14 volt circuit rises above 16.5 volts in Normal Mode for more than 0.012 seconds.
* 14 volt circuit rises above 16.0 volts in Jump-Assist Mode more than 0.012 seconds.

Action Taken When the DTC Sets

* The HPCM stores the DTC information in memory when the diagnostic runs and fails.
* The APM will shutdown14 volt conversion.

Conditions for Clearing the DTC

* 14 volt circuit falls below 16.3 volts in Normal Mode for more than 0.012 seconds.
* 14 volt circuit falls below 15.8 volts in Jump-Assist Mode for more than 0.012 seconds.

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.

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 Device Control APM 14 V Enable 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 14 V Device Control fails, replace the APM.

Repair Instructions

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