Expert: Roland Finston - 7/25/2011

Question
QUESTION: Hi,

I had intermittent hard to start problem that occurred rarely.  The last time it occurred I tried knocking here and there and I kinda shaked the TCM.  Then the car can start but it is not stable, ramp up and down by itself.  Then I found the lower connector of the TCM not inserted all the way until it clicked.  So I pushed it in and problem gone.  Then, one day I decided to clean the connectors.  I pull out both connectors and I use air duster to blow dust from the connectors' plug and socket. Next day I noticed the problem.  Everytime I slow down from high speed, the car jerks once when it reaches 30 mph and I can see that the rpm increases as though as a lower gear is engaged for a short time.

Is the problem a real physical problem? or is it related to disconnecting the TCM?  Is it possible that the car thinks I am installing a TCM from another car?

Regards,
Ahmad

ANSWER: Hi Ahmad,
What you are experiencing could be the unlocking of the torque converter lock-up clutch, which might better happen at around 40 mph rather than 30 mph. This may be controlled internally by the pcm/tcm on the electronic transaxle which you probably have. If you have the 2.4L engine then there may be a clutch solenoid that is electrically controlled and it has a 2-wire plug on the side of the transmission facing the front of the van. If so, check that plug. But that 2.4L engine would not have the 4-speed automatic transaxle with TCM which is mainly used on the 3.3/3.8L engine.
Roland

---------- FOLLOW-UP ----------

QUESTION: I am sorry I did not provide the details earlier.  The engine is 3.3L.  I will check that plug. Can you tell me which pin from the TCM is connected to the plug?

Thanks a lot for your 5 star response.

Answer
Hi Ahmad,
As far as I can tell from the wiring diagrams the torque converter clutch is not electrically controlled in the 4-speed transmission but rather hyrdraulically via the solenoid/pressure switch assembly which is located inside the box on the side of the transmission. I would be inclined to first get a fault code readout with a plug-in code reader to see if the tcm has a fault code stored in the memory that speaks about the tcc. Then decide what to do. An Autozone or similar nationwide parts store will often do that readout for free. Let me know any codes you find to be present. If the code indicates an issue with the assembly then that can be removed and replaced easily or even possible serviced if it is specifically tied to the tcc solenid inside of it.
Roland