Torque Converter Operation Test

WARNING: This page is about a different car, the 2010 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.

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

Carry out Quick Test with scan tool. Refer to the Introduction - Gasoline Engines article. Check for DTCs.
Connect a tachometer to the engine.
Bring the engine to normal operating temperature by driving the vehicle at highway speeds for approximately 15 minutes in Overdrive (Circle D) position.
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.
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 .
If the vehicle stalls in Overdrive (Circle D) or manual 2 at idle with vehicle at a stop, move the transmission range selector lever to manual 1 position. If the vehicle stalls, see torque converter operation concerns. Refer to Diagnosis By Symptom . If the vehicle does not stall in Overdrive (Circle D), refer to Diagnosis By Symptom .
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 procedures and the Introduction - Gasoline Engines article.

Spark plugs - check for cracks, high resistance or broken insulators
Plug wires
Fuel injector - filter may be plugged
Fuel contamination - engine runs poor
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

Torque Converter Road Evaluation Form
1) Does the torque converter engage/disengage?	Yes	Go to Step 2.
	No	REFER to Diagnosis By Symptom - Torque Converter No Apply Routine 240/340 and Always Applied Routine 241/341 for further diagnosis information. REPAIR as required, verify converter operation and then continue.
2) Does vibration occur during 3-4 or 4-3 shift at: light, medium or heavy throttle?	Light	May be torque converter clutch (TCC) shudder, go to Step 3.
	Medium	May be TCC shudder, go to Step 3.
	Heavy	Not TCC shudder - converter does not engage due to PCM strategy, REFER to NOISE, VIBRATION & HARSHNESS article and Diagnosis By Symptom - Noise/Vibration Routine 254/354 for further diagnosis.
3) Is the problem vehicle speed dependent, operating at steady speed (that is, 64 km/h [40 mph]) regardless of transmission range? Verify by manually selecting 2nd, OD cancel and OD.	Yes	Not TCC shudder, REFER to NOISE, VIBRATION & HARSHNESS article and the Diagnosis By Symptom - Noise/Vibration Routine 254/354 for further diagnosis.
	No	Go to Step 4.
4) Is the problem engine-RPM dependent (occurs at the same engine RPM independent of transmission gear)? Verify by holding same RPM in each transmission gear.	Yes	Not TCC shudder, REFER to NOISE, VIBRATION & HARSHNESS article and the Diagnosis By Symptom - Noise/Vibration Routine 254/354 for further diagnosis.
	No	Go to Step 5.
5) Does the problem occur in coast, steady speed or reverse range?	Yes	Not TCC shudder, REFER to NOISE, VIBRATION & HARSHNESS article and the Diagnosis By Symptom - Noise/Vibration Routine 254/354 for further diagnosis.
	No	Go to Step 6.
6) Does vibration occur during extended light brake application?	Yes	Not TCC shudder, REFER to NOISE, VIBRATION & HARSHNESS article, BRAKE SYSTEM - GENERAL INFORMATION article and Diagnosis By Symptom - Noise/Vibration Routine 254/354 for further diagnosis.
	No	Go to Step 7.
7) If one of the driving modes in Step 2 identifies a vibration which is not present in Steps 3-6, then there is a strong possibility that the vibration is caused by the TCC function. Carry out the repair procedures as found under Disassembly/Assembly.