P0AFF

DTC P0AFF

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 P0AFF
- System Voltage Too Low For Conversion

Diagnostic Fault Information






Circuit/System Description

The Accessory Power Module (APM) monitors its 14 volt circuit when it is enabled for charge or Jump Assist. It requires a minimum voltage on this circuit in order to begin operation. This DTC sets when the 14 volt circuit in the APM is below this minimum level at the time it is enabled. 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 at the APM is below 6.7 volts at 14 volt enable.

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 14 volt or 42 volt conversions to begin in this condition.

Conditions for Clearing the DTC

The 14 volt circuit at the APM rises above 6.7 volts.

Diagnostic Aids

The APM is protected from reverse polarity connections by a 200 amp in-line mega-fuse. The output current of the APM is lower than the fuse rating.

Circuit/System Verification

1. Start the Engine.
2. Check for any other DTCs.

Circuit/System Testing

1. Measure the voltage on the battery with a DMM. Make sure that it is fully charged, reading at least 12 Volts.
2. Remove the TPIM/APM Protective Cover. Remove the connector to the APM and connect a test light between the battery and the terminal. With a scan tool, verify that the output circuit in the APM is reading correctly.
3. Remove the battery cable connection to the APM and verify that the battery voltage has continuity to the terminal. Repair as necessary. If continuity is correct, replace cable terminal assembly to the APM.

Component Testing

Use APM Output Device Control to verify APM operation.

Repair Instructions

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

* 200-amp mega-fuse replacement
* 12 Volt Cable replacement (Megafuse to APM)