Diagnostic Instructions

DTC Descriptors

DTC P0A81: Hybrid Battery Pack Cooling Fan Control Circuit

DTC P0A82: Hybrid Battery Pack Cooling Fan Stuck Off

DTC P0A83: Hybrid Battery Pack Cooling Fan Stuck On

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
B+	P0A82	P0A82	--	--
Fan Control	P0A81, P0A83	P0A81, P0A82	P0A81	--

Circuit/System Description

The battery energy control module (BECM) monitors to detect if the cooling fan is enabled, in the stuck off position, or in the stuck on condition. If a failure is detected, the appropriate DTC will set.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

P0A81

P0A82

P0A83

Action Taken When the DTC Sets

The hybrid system is not affected.

Conditions for Clearing the DTC

P0A81

The fan state = RUN.

P0A82

The fan state is OFF.

P0A83

The fan state is ON.

Reference Information

Schematic Reference

Hybrid Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Starter Generator Control Module Cooling System Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 35616 GM Approved Terminal Test Kit

Circuit/System Verification

Ignition ON, using the scan tool special function command the hybrid cooling fan ON and OFF several times.

Circuit/System Testing

Warning: To help avoid personal injury, additional precautions must be taken prior to working on the generator control module or the generator starter. After removing the 36V battery cables from the generator battery, remove both engine wiring harness connectors from the generator control module. Wait at least 5 minutes and then remove the generator control module cover. Verify voltage levels at all 36V, 12V, and 3-phase connections, are less than 3 volts using a DMM before proceeding.

Warning: To help avoid personal injury, be careful when working in the vicinity of the generator battery disconnect control module. Internal components will still be live, 36V potential, even when the cover has been opened or removed.

Note: In order to avoid damaging BECM X1 and X2 connector terminals, the proper test probes should be used. The proper test probes are as follows:

P0A81

1. Ignition OFF, disconnect the cooling fan harness connector. Refer to Hybrid Battery Service Disconnect/Connect.
2. Disconnect BECM harness connector X2.
3. Test the cooling fan control circuit for an open or high resistance.

⇒	If the circuit tests normal, replace the BECM.

4. Replace the harness assembly.

P0A82

1. Ignition ON, command the hybrid battery pack cooling fan ON.

⇒	If the fan operates, replace the BECM.

2. Ignition OFF, disconnect the cooling fan harness connector. Refer to Hybrid Battery Service Disconnect/Connect.
3. Disconnect BECM harness connector X2.
4. Test the following circuits for an open or high resistance:

•	BECM X2 connector terminal 2 to cooling fan harness connector terminal 1

•	BECM X2 connector terminal 4 to cooling fan harness connector terminal 2

•	BECM X2 connector terminal 3 to cooling fan harness connector terminal 3

•	BECM X2 connector terminal 11 to cooling fan harness connector terminal 4

⇒	If all circuits test normal, replace the hybrid battery pack cooling fan.

5. Replace the harness assembly.

P0A83

1. Ignition OFF, disconnect the cooling fan harness connector. Refer to Hybrid Battery Service Disconnect/Connect.
2. Disconnect BECM harness connector X2.
3. Test the cooling fan control circuit for a short to ground.

⇒	If the circuit tests normal, replace the BECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.