P1A56

DTC P1A56

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P1A56

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Hybrid/EV System Voltage Discharge Circuit

Circuit/System Description

The power inverter module, often referred to as the drive motor generator power inverter module, contains DC high voltage capacitors and a resistor circuit intended to discharge the electrical energy stored within those capacitors. Whenever the high voltage contactors are opened, the hybrid powertrain control module connects the internal resistor circuit across the capacitor circuit. The level of the high voltage is monitored by the hybrid powertrain control module before and after the resistor circuit has been connected. If the voltage level remains high for too long, the hybrid powertrain control module sets this DTC and then commands the motor control modules to connect the drive motor generator 3 phase circuits across the DC high voltage positive and negative circuits thereby discharging the capacitors.

Conditions for Running the DTC

* The Vehicle is ON.

* The system voltage is at least 10 V.

* No high voltage DC sensor DTCs are present.

* High Voltage Contactors are commanded Open.

Conditions for Setting the DTC

Within 500 milliseconds after commanding contactors open, the high voltage bus voltage fails to decrease by at least 75 V.

Action Taken When the DTC Sets

* DTC P1A56 is a Type C DTC.

* The motor control modules are commanded to discharge the capacitor through the drive motor generator 3 phase stator circuits.

Conditions for Clearing the DTC

DTC P1A56 is a Type C DTC.

Diagnostic Aids

A high-pitched whine may emanate from the transmission assembly whenever the HV DC capacitance is discharged through the drive motor generator stator circuits.

Reference Information

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Circuit/System Verification

If the DTC is set, program the T6 power inverter module. If the DTC resets, replace the T6 power inverter module.

Repair Instructions

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

Control Module References Programming and Relearning for Drive Motor Generator Power Inverter Module, also called the power inverter module, replacement, programming, and setup.