P1ABC

DTC P1ABC

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 P1ABC
- 14 Volt Power Module Hybrid System Voltage Low

Circuit/System Description

The Accessory Power Module (APM) continuously monitors the High Voltage (300 volt) circuit during charge or Jump Assist. This DTC sets when the 300 volt circuit at the APM falls below 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 or APM 42 volt enable active.

Conditions for Setting the DTC

* 300 volt circuit is less than 215 volts in Normal Mode for more than 0.5 seconds.
* 300 volt circuit is less than 180 volts in Jump-Assist Mode for more than 0.5 seconds.

Action Taken When the DTC Sets

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

Conditions for Clearing the DTC

* 300 volt circuit is greater than 220 volts in Normal Mode for greater than 0.012 seconds.
* 300 volt circuit is greater than 185 volts in Jump-Assist Mode for greater than 0.012 seconds.

Diagnostic Aids

When in Normal Mode operation, the APM is drawing current from the 300 volt circuit while monitoring it. As long as the APM is not drawing current on an extremely low ESS, it has no direct control over the voltage on the high voltage circuit being too low. If other high voltage controllers are reporting the 300 volt circuit is low, the problem is not related to the APM.

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 180 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