P0AFE

DTC P0AFE

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 P0AFE
- Hybrid Battery System Voltage Too Low For Boost Conversion

Circuit/System Description

The Accessory Power Module (APM) controls the amount and direction of energy flowing between the high voltage (300 volt) direct current (DC) and low voltage (14 volt) DC. In Jump Assist operation, the APM receives both a High Voltage Setpoint and a Jump-Assist Enable command from the Hybrid Powertrain Control Module (HPCM) over the high speed hybrid GMLAN communication circuit. APM functions will run only when the APM Enable is active on the high speed hybrid GMLAN communication circuit.

Conditions for Running the DTC

APM Jump-Assist enable message active.

Conditions for Setting the DTC

300 volt circuit is below 194.0 volts when Jump-Assist Mode is enabled.

Action Taken When the DTC Sets

* The HPCM stores the DTC information in memory when the diagnostic runs and fails.
* The APM will not allow Jump-Assist 300 V conversions to begin in this condition.

Conditions for Clearing the DTC

300 V Circuit rises above 194.0 volts before enabling Jump-Assist Mode.

Diagnostic Aids

In Jump-Assist Mode, the APM is in control of applying the voltage to the high voltage circuit. The APM will not begin Jump-Assist if the high voltage circuit voltage is less than 194.0 volts.

Circuit/System Verification

Clear the DTCs, cycle the ignition to OFF and back ON and then retest for DTCs.

Circuit/System Testing

1. Turn the ignition to ON. Insure the High Voltage Contactor Relays are closed.
2. Observe the scan tool HPCM 300 V Circuit Voltage Signal parameter in the APM data list. The value should be more than the specified value listed above.

^ If the value is less than the specified value, the vehicle has a low drive motor generator battery condition.
^ If the value is more than the specified value, test the APM to PIM internal DC high voltage connections. Refer to Disassembly Procedure. If the terminal connections test good, replace the APM.

Repair Instructions

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