Torque Converter Operation Test
Torque Converter Operation Test
This test verifies that the Torque Converter Clutch (TCC) control system and the torque converter are operating correctly.
1. Carry out Self-Test with scan tool. Refer to Computers and Control Systems Information. Check for DTCs.
2. Connect a scan tool.
3. Bring the engine to normal operating temperature by driving the vehicle at highway speeds in (D) position.
4. After normal operating temperature is reached, maintain a constant vehicle speed of about 80 km/h (50 mph) and tap brake pedal with the left foot.
5. 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 operation concerns. Refer to Diagnosis By Symptom Diagnosis By Symptom.
6. If the vehicle stalls in (D) or manual 2 at idle with vehicle at a stop, move the selector lever to manual 1 position. If the vehicle stalls, see torque converter operation concerns. Refer to Diagnosis By Symptom Diagnosis By Symptom. If the vehicle does not stall in (D), refer to Diagnosis By Symptom Diagnosis By Symptom.
7. If the vehicle exhibits a vibration during the road test, complete the Road Test Evaluation Form. This form will aid the technician in determining the source of the vibration.
NOTE: The following is a list of common vehicle concerns that have been misdiagnosed as TCC shudder. For diagnosis of the following items, refer to the appropriate systems of the diagnostic/repair information and Computers and Control Systems Information.
- Spark plugs - check for cracks, high resistance or broken insulators
- Ignition coil-on-plug - short or open circuit
- Fuel injector - filter may be plugged
- Fuel contamination - engine driveability concerns
- 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) and 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
