Chrysler Repair: 98 Sebring Transmission, transmission control module, diagnostic abilities

Question
My car changes gears without problems, then in about a few days the "check engine" light comes on and the car jerks out of gear and won't shift. I pull the car over, turn off the engine, wait a few minutes then the car starts shifting again.  I took it to the mechanic and he replaced the Transmission Control Module but that didn't help.  He said that I might need to change out the transmission.  But why does the transmission work sometimes.  Could there be some other part that needs to be replaced besides the transmission.

Answer
Hi Martha,
I wonder whether your mechanic just tried the old "throw a part at it to see if that fixes it" approach?
The trans and the engine are both computer controlled and have self-diagnostic abilities. When the trans refuses to shift it means that it has recognized a problem and put itself into a mode where the fewest parts are required so that you will get a readout of ite memory to tell you what is the problem it has recognized. That is called limp-in mode. What you need is to get a shop that has a diagnostic reader to plug it into a socket under the dash and ask the transmission "what is wrong". The answers are four digit code numbers prefaced with a P. Then ask them what it means, what they would recommend and how much cost. Then write me back with the numbers and we'll compare notes with the Chrysler shop manuals. You may be able to get a free readout at part stores such as Autozone.
But in any case you might ask you mechanic if he read the codes before he threw the module at the problem and if so what was the number. If he didn't, then I think he should take the module back and give you back your old one and refund your money.
I look forward to hearing what you learn.
Roland