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 a good torque converter. Only after a complete diagnostic evaluation can the decision be made to install a new or remanufactured 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 Clutch (TCC) Operation Test. Refer to Torque Converter Operation Test.

4. Carry out diagnostic procedures.

- Run On-Board Diagnostic (OBD). See On-Board Diagnostics with Scan Tool. Refer to Diagnostics Diagnostics.
- Repair all non-transmission related DTCs first.
- Repair all transmission DTCs.
- Rerun OBD test 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 service as necessary before servicing the torque converter.


Torque Converter Operation Test

This test verifies that the TCC control system and the torque converter are operating correctly.

1. Carry out the Self Test. See On-Board Diagnostics with Scan Tool. Refer to Diagnostics Diagnostics. Check for DTCs. Refer to the Diagnostic Trouble Code (DTC) Charts 5R55S - Automatic Transaxle/Transmission.

2. Connect a scan tool to the vehicle and monitor engine rpm.

3. Bring the engine to normal operating temperature by driving the vehicle at highway speeds in the (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 the brake pedal is tapped and decrease about 5 seconds after the pedal is released. If this does not occur, refer to Torque Converter Operation Concerns in Diagnosis By Symptom Diagnosis By Symptom.

6. If the vehicle stalls in (D) or MANUAL 2 at idle with the vehicle stopped, move the selector lever to MANUAL 1 position. If the vehicle stalls, refer to Diagnosis By Symptom Diagnosis By Symptom, Torque Converter Operation Concerns. Repair as necessary. If the vehicle does not stall in (D), refer to Diagnosis By Symptom Diagnosis By Symptom.