P1AF2

DTC P1AF0 or P1AF2

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 P1AF0
- Drive Motor 1 Control Module Hybrid Battery Voltage System Isolation Lost

DTC P1AF2
- Drive Motor 2 Control Module Hybrid Battery Voltage System Isolation Lost

Circuit/System Description

The drive motor generator power inverter control module (PIM) contains two motor control modules (MCMs). Each MCM measures hybrid battery high voltage (HV) with several internal sensors. The MCMs test for loss of isolation (LOI) between either the HV positive circuit or HV negative circuit and vehicle chassis.

LOI is detected through the use of two high-impedance resistors and voltage measuring circuitry. The two resistors are connected in series between the HV positive and HV negative circuits. The center connection of the two resistors is also connected to vehicle chassis. The MCM then measures the voltage drop across one of the resistors. Without a loss of isolation, the MCM should measure about half of the high voltage potential. This is referred to as mid-pack voltage. The Mid-pack voltage value is then doubled by the software and displayed on a scan tool as Motor 1 Isolation Voltage or Motor 2 Isolation Voltage. When a loss of isolation is present, the motor isolation voltage display will indicate voltage that is more or less than actual hybrid battery high voltage.

Conditions for Running the DTC

* The high voltage contactor relays are closed.
* Ignition voltage is 8-18 volts.

Conditions for Setting the DTC

The ratio between Mid-Pack Voltage and hybrid battery high voltage is less than 0.27 or more than 1.85.

OR

* Mid-Pack Voltage is less than 35 V or more than 975 V.
* Either above condition exists for 52.08 seconds.

Action Taken When the DTC Sets

* DTCs P1AF0 and P1AF2 are Type C DTCs.
* The PIM commands the battery energy control module (BECM) to open the high voltage relay contactors.

Conditions for Clearing the DTC

DTCs P1AF0 and P1AF2 are Type C DTCs.

Circuit/System Verification

Important: DTC P1AE7 must test and pass before performing this diagnostic procedure.

1. Inspect for DTC P1AE7.

^ If the DTC is set, the loss of isolation has occurred within the drive motor generator battery. Refer to DTC P1AE6 or P1AE7. P1AE6

2. Clear the DTC information.
3. Turn the ignition OFF for 1 minute.
4. Turn the ignition ON.
5. Operate the vehicle within the conditions for running and setting.
6. Retest for DTCs P1AF0 and P1AF2.

Circuit/System Testing

Important: DTC P1AE7 must test and pass before performing this diagnostic procedure.

1. Inspect for DTC P1AE7.

^ If the DTC is set, the loss of isolation has occurred within the drive motor generator battery. Refer to DTC P1AE6 or P1AE7. P1AE6

2. Place the vehicle in the following condition:

* Ignition ON
* Engine OFF
* Hood Closed
* Transmission in Park
* High voltage contactor relays Closed

3. Observe the HPCM 300 V Circuit Voltage display with the scan tool. Compare this value to the MCM 1 Isolation Voltage display. With no loss of isolation currently present, these values should be within 20 V of each other.

^ If the values are not within the indicated range, replace the PIM, accessory DC power control module (APM), air conditioning compressor module (ACCM) and the Battery Positive and Negative 300 V Cable (DC) assembly.
^ If the values are within the indicated range, proceed to Motor Phase Testing.

Motor Phase Testing
1. Perform the Motor 1 Isolation Test output control with the scan tool. While observing the Motor 1 Isolation Voltage activate the Short to Positive command.

^ If the Motor 1 Isolation Voltage is not within 20 V of the HPCM 300 V Circuit Voltage value when the phases are shorted, replace drive motor generator 1 and the 3 phase cable assembly.

2. Perform the Motor 2 Isolation Test output control with the scan tool. While observing the Motor 2 Isolation Voltage activate the Short to Positive command.

^ If the Motor 2 Isolation Voltage is not within 20 V of the HPCM 300 V Circuit Voltage value when the phases are shorted, replace drive motor generator 2 and the 3 phase cable assembly.
^ If the Motor 2 Isolation Voltage is within 20 V of the HPCM 300 V Circuit Voltage value when the phases are shorted, replace the PIM.

Repair Instructions

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

* Drive Motor Battery Positive and Negative Cable Replacement for Battery Positive and Negative 300 V Cable (DC) assembly.
* Compressor Replacement (LY2, LY5, LH6, L76, L92 and LMG) Compressor Replacement (HP2) for air conditioning compressor (RPO HP2) replacement.
* Drive Motor Generator Power Inverter Module Cable Removal for 3 phase cable replacement.
* Drive Motor with Generator Assembly Removal - 1st Position for Drive Motor Generator 1 replacement.
* Drive Motor with Generator Assembly Removal - 2nd Position for Drive Motor Generator 2 replacement.