P0A81
DTC P0A81
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (with HP2) (Initial Inspection and Diagnostic Overview)Diagnostic System Check - Vehicle (without HP2) (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
DTC Descriptor
DTC P0A81
- Hybrid Battery Pack Cooling Fan Control Circuit
Typical Scan Tool Data
Circuit/System Description
The drive motor generator battery is cooled by a drive motor battery vent fan motor. The battery vent fan motor and battery vent fan relay are located inside the drive motor generator battery assembly. B+ to the battery vent fan is provided from the battery vent fan relay when the drive motor generator battery control module (GBCM) supplies a ground to the battery vent fan relay. A grounding wire from the battery vent fan motor assembly completes the path to case ground. A 5 V circuit is provided from the battery vent fan motor assembly, to the GBCM. The GBCM uses a pulse width modulated (PWM) signal on the 5 V circuit to control the battery vent fan motor duty cycle. The battery vent fan motor also supplies an additional 5 V signal that indicates vent fan speed back to the GBCM, the lower the voltage the greater the fan speed. The GBCM uses 4 battery temperature sensors, one air inlet duct and one air outlet temperature sensor to control battery vent fan motor operation and speed.
Conditions for Running the DTC
* The ignition is ON.
* Battery voltage is 9-18 V.
* The fan speed is commanded 35 percent or greater.
Conditions for Setting the DTC
Fan control signal monitor voltage to GBCM is greater than 2.3 V or less than 0.5 V for 5 seconds.
Action Taken When the DTC Sets
DTC P0A81 is a type B DTC.
Conditions for Clearing the DTC
DTC P0A81 is a type B DTC.
Diagnostic Aids
Verify the GBCM fan fuse is not open.
Reference Information
Schematic Reference
Hybrid Cooling Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Drive Motor Generator Battery Cooling Description (Drive Motor Generator Battery Cooling Description)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Special Tools
EL-48900 HEV Safety Kit
Circuit/System Verification
Ignition ON, command the battery pack vent fan speed to 60 percent duty cycle with a scan tool. The battery pack vent fan should turn ON.
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. Ignition OFF, disable the high voltage at the drive motor generator battery. Refer to High Voltage Disabling (High Voltage Disabling).
2. Remove the drive motor generator battery case upper cover, front cover, and right side cover.
3. Disconnect the harness connector at the battery vent fan motor.
4. Connect a test lamp between the ignition circuit terminal 2 and ground.
5. Ignition OFF, connect the 12 V battery.
6. Ignition ON, command the battery pack vent fan speed to 60 percent. The test lamp should illuminate after a 5-7 second delay.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
7. Verify a test lamp illuminates between B+ and the ground circuit terminal 3.
• If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
8. Ignition OFF, connect the harness connector at the battery vent fan motor.
9. Disconnect X2 harness connector at the GBCM.
10. Verify a test lamp illuminates between the vent fan relay control circuit terminal 7 and ground.
• If the test lamp does not illuminate, test the control circuit for an open/high resistance. If the circuit tests normal, replace the generator battery vent fan relay.
11. Connect a 3 A fused jumper wire between the vent fan motor relay control circuit terminal 7 and ground.
12. Ignition ON, test for 4.8-5.2 V between the signal circuit terminal 2 and ground.
• If the voltage is not within the specified range, test the signal circuit for a short to voltage, short to ground, or an open/high resistance. If the circuit tests normal, replace the generator battery vent fan.
13. If all circuits test normal, replace the drive motor generator battery control module.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Generator Battery Vent Fan Replacement (Generator Battery Vent Fan Replacement)
* Generator Battery Vent Fan Relay Replacement (Generator Battery Vent Fan Relay Replacement)
* Control Module References (Programming and Relearning) - for drive motor generator battery control module replacement, setup and programming.