Torque Converter Operation Test

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. Carry out Quick Test with scan tool. Refer to Computers and Control Systems. Check for DTCs.
2. Connect a scan tool to the vehicle.
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 speed of about 56 km/h (35 mph) in 5th gear for 10 seconds.
5. Release the accelerator pedal and monitor the scan tool TP voltage to approximately 1.25 volts or 30% throttle.
6. Monitor the TCC and engine speed PID. The TCC should release and engine rpms should increase before the 5-4 shift occurs.

NOTE: This is a list of common vehicle concerns that have been misdiagnosed as TCC shudder. For diagnosis of these items, refer to the appropriate information and Computers and Control Systems.

^ Spark plugs - check for cracks, high resistance or broken insulators
^ Plug wires
^ Fuel injector - filter may be plugged
^ Fuel contamination - engine driveability concerns
^ Exhaust gas recirculation (EGR) valve - valve may let in too much exhaust gas and cause engine to run lean
^ Vacuum leak - engine will not get correct air/fuel mixture
^ Manifold absolute pressure (MAP)/mass air flow (MAF) sensor - incorrect air/fuel mixture
^ Heated oxygen sensor (HO2S) - too rich/lean air/fuel mixture
^ Fuel pressure - may be too low
^ Engine mounts - loose/damaged mounts can cause vibration concerns
^ Axle joints - check for vibration