I have a 2005 Dodge Grand caravan 3.8L the transmission has erract behavior like shuttering but when you let off gas it corrects itself (sometimes). My question is where is the transmission control module located? Is the tcm and PCM them same

 

I can toss out some ideas, I just went through some transmission issues on my 1993 Caravan .... 3.3 V6/automatic.

My TCM is on the firewall ... I do not think you have one because rockauto does not list one for your vehicle. So it probably is combined with the computer.

My advice is to check all your electrical connections that all your pins are clean and no corrosion. ..... I spent about $500 replacing all my sensors,tcm and found out it was a dirty connection causing the issue.

Your transmission appears to be similar .... several years ago I had a issue where the bolt holding the harness plug to the shift sensor cam loose, and just needed tightened.


Your shift sensor looks like mine. Above the shift sensor on the left is the input speed sensor and on the right hidden in the shadows is the output sensor. Possible these 2 sensors could be a issue or have dirty connections. They have some sort of control over speed. Below and to the right is the prndl sensor I doubt that is your issue but check the wiring. The reverse lights is around the corner .... not your issue either.

Actually I have a better photo. I would check all the wiring connections on the transmission and follow the harness back to the pcm .... mine split off and went to the battery and got power there for the tcm that you do not have .... but follow it and look for dirty connections.

Then if you want to throw $$ at it, I would first start with the input/output sensors .... $10-$15 each at Rockauto.
The shift sensor is more spendy at $150-$200 for my van. ..... Not sure I would want to spend that $$ without a proper diagnoses ..... your call though.



Our transmissions are over 10 years apart, but they used the same design for many years and I'm guessing yours is pretty close to mine.

 

2005 minivans have two modules. You may find them behind the left (driver side) headlamp. There also a mid year change on the 41TE (AKA A604) You may need to find an adapter TRS ( Transmission Range Sensor). Some TRS round pin connections and some were flat.

 

This is my transmission and PCM wiring