Torque Converter Diagnosis

Torque Converter Diagnosis





Prior to installing a new torque converter, all diagnostic procedures must be followed. This is to prevent the unnecessary installation of new or remanufactured torque converters. Only after a complete diagnostic evaluation can the decision be made to install a new torque converter.

Begin with the normal diagnostic procedures as follows:

1. Preliminary Inspection.

2. Know and Understand the Customer Concern.

3. Verify the Concern - Carry out the Torque Converter Operations Test; refer to Torque Converter Operations Test.

4. Carry out Diagnostic Procedures.

- Run On-Board Diagnostic (OBD); refer to OBD with Scan Tool.
- Repair all non-transaxle related DTCs first.
- Repair all transaxle DTCs.
- Rerun OBD to verify repair.

- Carry out the Line Pressure Test. Refer to Special Testing Procedures Special Testing Procedures.
- Carry out the Stall Speed Test. Refer to Special Testing Procedures Special Testing Procedures.
- Carry out the Diagnosis by Symptom Index. Refer to Diagnosis By Symptom Diagnosis By Symptom.
- Use the index to locate the appropriate routine that best describes the symptom(s). The routine will list all possible components that may cause or contribute to the symptom. Check each component listed; diagnose and repair as necessary before installing a new or remanufactured torque converter.


Torque Converter Operations Test

This test verifies that the Torque Converter Clutch (TCC) control system and the torque converter are operating correctly.

1. Carry out the Self Test. Refer to On-Board Diagnostic (OBD) with Scan Tool. Check for DTCs. Refer to Diagnostic Trouble Code (DTC) Charts FNR5

2. Connect a scan tool.

3. Bring the engine to normal operating temperature by driving the vehicle at highway speeds for approximately 15 minutes in D position.

4. After normal operating temperature is reached, maintain a constant vehicle speed of about 80 km/h (50 mph) and tap the brake pedal with the left foot.

5. The engine rpm should increase when brake pedal is tapped, and decrease about 5 seconds after pedal is released. If this does not occur, see Torque Converter Clutch (TCC) Operation Concerns. Refer to Diagnosis By Symptom Diagnosis By Symptom.

6. If the vehicle stalls in D at idle with vehicle at a stop, move the position selector lever to L position. If the vehicle stalls, refer to Torque Converter Clutch (TCC) Operation Concerns in the Diagnosis By Symptom Diagnosis By Symptom. Repair as necessary. If the vehicle does not stall in D position. Refer to Diagnosis By Symptom Diagnosis By Symptom.