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P0A79




DTC P0A78 or P0A79

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 P0A78

-
Drive Motor 1 Inverter Performance

DTC P0A79

-
Drive Motor 2 Inverter Performance

Circuit/System Description

The power inverter module, often referred to as the drive motor generator power inverter module, contains the two drive motor control modules. Each motor control module operates its respective drive motor generator based upon hybrid/EV powertrain control module commands. Each motor control module controls the speed, direction and output torque of its respective drive motor generator through the sequencing actuation of high current switching transistors called insulated gate bipolar transistors. Each insulated gate bipolar transistor assembly is monitored for fault conditions. The motor control modules are part of the power inverter module and are not serviced separately.

Conditions for Running the DTC

The high voltage contactor relays are closed.

Conditions for Setting the DTC

The motor control module detects excessive current flow through the switched portion of the insulated gate bipolar transistor.

Action Taken When the DTC Sets

* DTCs P0A78 and P0A79 are Type A DTCs.

* The power inverter module requests hybrid powertrain control module 2 to open the high voltage contactor relays.

Conditions for Clearing the DTC

DTCs P0A78 and P0A79 are Type A DTCs.

Reference Information

Schematic Reference

Hybrid Controls Schematics Hybrid Controls Schematics

Connector End View Reference

Component Connector End Views Hybrid/EV Battery Pack X1

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

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, clear DTC; Turn the vehicle OFF for 2 minutes. Turn vehicle ON, Operate vehicle within conditions for running and setting DTC. If the DTC resets, go to Circuit/System Testing.

Circuit/System Testing

Danger:
Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.


The High Voltage Disabling procedure will perform the following tasks:


* Identify how to disable high voltage.


* Identify how to test for the presence of high voltage.


* Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.


Failure to follow the procedures exactly as written may result in serious injury or death.


1. Perform the High Voltage Disabling High Voltage Disabling procedure for servicing the T6 Power Inverter Module Assembly or T12 Transmission.

2. Remove the 3-phase cable assembly from the power inverter module distribution box. Refer to Drive Motor Generator Rotor and Stator Removal - Unit A Drive Motor Generator Rotor and Stator Removal - Unit A or Drive Motor Generator Rotor, Stator, and Output Sun Gear Shaft Removal - Unit B Drive Motor Generator Rotor, Stator, and Output Sun Gear Shaft Removal - Unit B.

3. Test for infinite resistance between the Phase Terminals listed below and ground for each phase of the appropriate M15 drive motor:

Drive Motor 1

* X5 terminal 3 phase U

* X5 terminal 2 phase V

* X5 terminal 1 phase W

Drive Motor 2

* X6 terminal 3 phase U

* X6 terminal 2 phase V

* X6 terminal 1 phase W

• If not the specified value, test the AC circuit for a short to ground or a short between the AC circuit terminals and the aluminum cable mounting block. If the circuit tests normal, replace the T6 power inverter module. If the DTC resets replace the M15 drive motor.


Repair Instructions

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

* Drive Motor Generator Rotor and Stator Removal - Unit A Drive Motor Generator Rotor and Stator Removal - Unit A for Drive Motor 1 or Drive Motor 1 3-Phase Cable Assembly replacement

* Drive Motor Generator Rotor, Stator, and Output Sun Gear Shaft Removal - Unit B Drive Motor Generator Rotor, Stator, and Output Sun Gear Shaft Removal - Unit B for Drive Motor 2 or Drive Motor 2 3-Phase Cable Assembly replacement

* Control Module References Programming and Relearning for power inverter module, often referred to as the Drive Motor Generator Power Inverter Module, replacement, programming, and setup.

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