Torque Converter Operation Test

WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

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

Carry out Quick Test with diagnostic tool. Refer to the INTRODUCTION - GASOLINE 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 (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 (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 (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 torque converter clutch shudder. For diagnosis of the following items, refer to the appropriate articles and the refer to the INTRODUCTION - GASOLINE 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.
MAP/MAF sensor - improper air/fuel mixture.
HO2S sensor - 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 REFERENCE

Torque Converter Road Evaluation Form
1) Does the Torque Converter Engage/Disengage?	Yes	GO to Step 2.
1) Does the Torque Converter Engage/Disengage?	No	REFER to DIAGNOSIS BY SYMPTOM - TORQUE CONVERTER CLUTCH OPERATION CONCERNS: NO APPLY and TORQUE CONVERTER CLUTCH OPERATION CONCERNS: ALWAYS APPLIED/STALLS VEHICLE 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 shudder, GO to Step 3.
	Medium	May be torque converter clutch shudder, GO to Step 3.
	Heavy	Not torque converter clutch shudder - converter does not engage due to PCM strategy, REFER to NOISE, VIBRATION & HARSHNESS article and OTHER CONCERNS: NOISE/VIBRATION - FORWARD OR REVERSE , Routine 254/354 for further diagnosis.
3) Is the problem vehicle speed dependent, operating at steady speed, i.e., 64 km/h (40 mph) regardless of transmission range? Verify by manually selecting 2nd, OD cancel, and OD.	Yes	Not torque converter clutch shudder, REFER to NOISE, VIBRATION & HARSHNESS article and OTHER CONCERNS: NOISE/VIBRATION - FORWARD OR REVERSE , 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 torque converter clutch shudder, REFER to NOISE, VIBRATION & HARSHNESS article and OTHER CONCERNS: NOISE/VIBRATION - FORWARD OR REVERSE , 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 torque converter clutch shudder, REFER to NOISE, VIBRATION & HARSHNESS article and OTHER CONCERNS: NOISE/VIBRATION - FORWARD OR REVERSE , Routine 254/354 for further diagnosis.
	No	GO to Step 6.
6) Does vibration occur during extended light brake application?	Yes	Not torque converter clutch shudder, REFER to NOISE, VIBRATION & HARSHNESS article and OTHER CONCERNS: NOISE/VIBRATION - FORWARD OR REVERSE , 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 torque converter clutch function. Carry out the repair procedures as found under Disassembly/Assembly.