Torque Converter Diagnosis

Torque Converter Diagnosis





Prior to torque converter installation, perform all diagnostic procedures. This is to prevent the unnecessary installation of new or remanufactured torque converters.

Torque Converter Operation Test

The Torque Converter Operation Test verifies that the Torque Converter Clutch (TCC) control system and the torque converter are operating correctly.

1. Connect a scan tool to the vehicle and check for DTCs.

2. Bring the engine to normal operating temperature by driving the vehicle at highway speeds in the (D) position.

3. After normal operating temperature is reached, maintain a constant speed of about 56 km/h (35 mph) in 5th gear for 10 seconds.

4. Release the accelerator pedal and monitor the scan tool Throttle Position (TP) 1 voltage to approximately 1.25 volts or 25% throttle.

5. Monitor the TCC and RPM PID. The torque converter should unlock and engine rpm should increase before the 5-4 shift occurs.

Torque Converter Clutch Mechanical Operation Test

The torque converter clutch (TCC) mechanical operation can be isolated to evaluate clutch function. Using the scan tool and the active command PID the symptom can be eliminated by turning the TCC on or off.

1. Ignition ON

2. Enter the following diagnostic mode on the scan tool: PCM (gas) TCM (diesel) DataLogger.

NOTE: The vehicle must be moving at speeds of 56 km/h (35mph) or higher to enable the active command.

3. Select the (TCC_OSC) active command. Command the TCC Off.

4. If the concern is still present, proceed with transmission diagnostics, if the concern is not present replace the torque converter.