Differential Oil Cooler Malfunction (Coupe)
Differential Oil Cooler Malfunction (Coupe)
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.
Diagnostic Fault Information
Circuit/System Description
The differential cooler is designed to reduce the temperature of the rear differential fluid during high speed driving. The differential cooler system is controlled by a temperature switch located in the rear of the differential housing and functions when conditions require it to operate. The fluid capacity for the rear differential cooler is greater than the standard system.
Reference Information
Schematic Reference
Rear Axle Schematics Electrical Diagrams
Connector End View Reference
Component Connector End Views A/C Compressor Clutch
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
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Testing
Note:
Allow the differential housing temperature to adjust to approximate ambient air temperature before performing any testing.
1. Ignition OFF, disconnect the differential cooler pump relay 1.
2. Test for less than 10 ohms between the ground terminal A1 and ground.
• If greater than the specified value, repair the open/high resistance in the ground circuit.
3. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal A2 and ground.
• If the test lamp illuminates, test the control circuit for a short to voltage.
4. Verify that a test lamp illuminates between the ignition circuit terminal C2 and ground.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test or replace the differential cooler pump relay.
5. Verify that a test lamp illuminates between the B+ circuit terminal C1 and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test both differential cooler pump relay 1 and relay 2 control circuits terminals A2 for a short to ground. If the circuits test normal, test or replace the differential cooler pump.
6. Ignition OFF, reconnect differential cooler pump relay 1.
7. Disconnect the differential cooler pump relay 2.
8. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal A2 and ground.
• If the test lamp illuminates, test the control circuit for a short to voltage.
9. Verify that a test lamp illuminates between the ignition circuit terminal C2 and ground.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, test or replace the differential cooler pump relay 2.
10. Verify that a test lamp illuminates between the B+ circuit terminal C1 and ground.
• If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
11. Ignition OFF, reconnect differential cooler pump relay 2.
12. Ignition ON, disconnect the harness connector at the differential temperature switch.
• If the differential coolant pump was activated and deactivates when disconnected, replace the differential temperature switch.
13. Ignition OFF, test for less than 10 ohms between the ground terminal B and ground.
• If greater than the specified value, repair the open/high resistance in the ground circuit.
14. Test for infinite resistance between the control terminal A and ground.
• If less than the specified value, test for a short to ground in the relay 2 coil control circuit. If the circuit tests normal, replace the differential cooler pump relay 2.
15. Ignition ON, momentarily install a 5 A fused jumper between the relay 2 coil control circuit terminal A and the ground circuit terminal B.
• If the differential coolant pump activates, replace the differential temperature switch.
16. Ignition OFF, disconnect the harness connector at the differential cooler pump.
17. Test for less than 10 ohms between the differential cooler pump ground circuit terminal 2 and ground
• If greater than the specified range, repair the open/high resistance in the ground circuit.
18. Ignition ON, verify a test lamp does not illuminate between the differential cooler pump control circuit terminal 1 and ground.
• If the test lamp illuminates, test for a short to voltage on the pump control circuit. If the circuit tests normal, test or replace the differential cooler pump relay 2.
19. Install a 5 A fused jumper between the differential temperature switch control circuit terminal A and the ground circuit terminal B.
20. Verify a test lamp illuminates between the differential cooler pump control circuit terminal 1 and ground circuit terminal 2
• If the test lamp does not illuminate, test the relay 2 coil control and pump control circuits for an open/high resistance. If all circuits test normal, test or replace the differential cooler pump relay 2.
21. If all circuits test normal, test or replace the differential cooler pump.
Component Testing
Relay Test
1. Ignition OFF, disconnect the differential cooler pump relay.
2. Test for 60-180 ohms between terminals C2 and A1.
• If not within the specified range, replace the differential cooler pump relay.
3. Test for infinite resistance between the following terminals:
* C1 and C2
* C1 and A2
* C1 and A1
* A1 and A2
• If not the specified value, replace the differential cooler pump relay.
4. Test for less than 2 ohms between terminals C1 and A2.
• If greater than the specified range, replace the differential cooler pump relay.
5. Install a 20 A fused jumper wire between relay terminal C2 and B+. Install a jumper wire between relay terminal A1 and ground. Test for less than 2 ohms between terminals C1 and A2.
• If greater than the specified range, replace the differential cooler pump relay.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Differential Oil Cooler Temperature Sensor Replacement Differential Oil Cooler Temperature Sensor Replacement
* Intermediate Axle Differential Lubricant Pump Replacement Intermediate Axle Differential Lubricant Pump Replacement