P1A56

DTC P1A56

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 Descriptors

DTC P1A56
- Hybrid System Voltage Discharge Circuit

Circuit/System Description

The drive motor generator power inverter module assembly (PIM) contains capacitors and a resistor circuit intended to discharge the electrical energy stored within the capacitors. Whenever the high voltage contactor relays are opened, the hybrid powertrain control module (HPCM) connects an internal resistor circuit across the high voltage positive and negative circuits. If high voltage is monitored by the HPCM after the resistor circuit has been connected, the HCPM commands the motor control modules (MCMs) to connect the motor phase circuits across the DC high voltage (HV) positive and negative circuits. If high voltage is not monitored after the motor phase circuits are connected, this DTC will set. If high voltage is monitored by the HPCM after the motor phase circuits have been connected, a stuck-closed high voltage contactor relay DTC is set.

Conditions for Running the DTC

The hybrid powertrain control module (HPCM) commands the battery energy control module (BECM) to open the high voltage contactor relays.

Conditions for Setting the DTC

High voltage is present at the PIM after the BECM has connected the internal discharge resistor and is not present after the HPCM has connected the motor phase circuits between the DC HV positive and negative circuits.

Action Taken When the DTC Sets

DTC P1A56 is a Type C DTC.

Conditions for Clearing the DTC

DTC P1A56 is a Type C DTC.

Circuit/System Testing

1. Capture and then clear DTC information with the scan tool.
2. Ignition ON, observe the BECM Contactor System Status parameter with the scan tool. The parameter should indicate the HV contactor relays are Closed.
3. Turn the ignition OFF and wait 2 minutes.
4. Turn the ignition ON and observe the DTCs with the scan tool.

^ If DTC P1A56 resets, replace the PIM.

Repair Instructions

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