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 P0A8E: 14 Volt Power Module System Voltage HighCircuit/System Description
The Accessory Power Module (APM) continuously monitors its 14 volt circuit during Normal mode and 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 16.0 volts in Normal mode for more than 0.012 seconds. |
| • | 14 volt circuit rises above 16.0 volts in Jump Assist mode for more than 0.012 seconds. |
Action Taken When the DTC Sets
| • | DTC P0A8E is a Type C DTC. |
| • | The HPCM stores the DTC information in memory when the diagnostic runs and fails. |
| • | The APM will shutdown 14 volt conversion. |
Conditions for Clearing the DTC
| • | 14 volt circuit falls below 15.7 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. |
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Drive Motor Generator Control Module Description and Operation
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Verify with the scan tool that the BCM is reading the voltage correctly.
Circuit/System Testing
- Turn the Ignition to ON.
- Connect a DMM to the 14 volt battery.
- 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 after completing the diagnostic procedure.
Control Module References for APM replacement, setup, and programming.
