Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC P0A84: Hybrid Battery Pack Cooling Fan Control Circuit Low VoltageDTC P0A85: Hybrid Battery Pack Cooling Fan Control Circuit High Voltage
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Cooling fan tach feedback | P0A84 | P0A84 | P0A85 | P0A84, P0A85 |
Circuit/System Description
The battery energy control module (BECM) monitors the generator battery vent fan speed to detect if the fan speed is less than or greater than commanded. If a failure is detected, the appropriate DTC will set.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
P0A84
| • | Fan control feedback is less than 5 percent. |
| • | Fan state is ON. |
P0A85
| • | Fan control feedback is greater than 95 percent. |
| • | Fan state is ON. |
| • | Fan command is less than 80 percent. |
Action Taken When the DTC Sets
The hybrid system is disabled.
Conditions for Clearing the DTC
P0A84, P0A85
The fan speed control feedback is normal.
Reference Information
Schematic Reference
Connector End View Reference
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
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.
- Verify the DTC is set current, clear the DTC.
- Ignition ON, using the scan tool special function command the generator battery vent fan ON and OFF several times.
| ⇒ | If the generator battery vent fan operates as commanded and the DTC resets, refer to Circuit/System Testing. |
| ⇒ | If the generator battery vent fan does not operate as commanded , replace the generator battery vent fan. |
Circuit/System Testing
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:
| • | J-35616-65B for female terminals |
| • | J-35616-64B for male terminals |
- Ignition OFF, disconnect generator battery vent fan harness connector. Refer to Hybrid Battery Service Disconnect/Connect.
- Disconnect BECM harness connector X2.
- Test the fan tach feedback circuit X2 connector terminal 11 to cooling fan harness connector terminal 4 for a short to voltage or a short to ground.
- If the circuit test normal replace the BECM.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BECM replacement, setup, and programming |
