QuestionI have a 95 chrysler cirrus, 2.5 liter 4 speed auto with air. The transmission had a leak and was not shifting properly. We were advised by 3 different mechanics to replace the transmission because running it with low transmission fluid the belts and things would probably have to be replaced and the cost would be the same, well around the same. With the year of the car we decided to just get a used transmission to keep the cost down, we've since had it replaced and still the car will not shift. We've bought a book on the car and my husband thinks he's narrowed it down to the powertrain control module. When he wiped and scraped debri from the connector it shifted through all the gears perfectly,,,,,,,,,once,,,and hasen't again. So we are pretty sure that the transmission is good. None of the guages on the dash are working, there is a no bus code when starting the car. We have looked for the powertrain control module, we want to buy it used because of the expense. We have not been able to find one. Also my husband replaced the battery and didn't use the same type as came with the car, it installed differently, could this have caused any problems with the car. We've gotten so many opinions on this subject. We are sure that the powertrain controls both the bodycontrol which controls the guages and the transmission control which allows the transmission to work, so after doing the test in the manual we are almost sure or hopeful that it is the powertrain that we need. we've been told that when you replace the transmission that you have to reprogram the powertrain is this so? can it be done at home , if we take it to a dealer we are afraid of the cost, we have too much tied up in this car, i've asked about this subject before in a previous post and was very satisfied with the response, but am still pulling my hair out over this car.
AnswerHi Kimberly,
I don't believe the powertrain controller is likely to be the cause of the problem with your transmission. Although the engine and the trans controllers share information about the operation of the vehicle on what is called the data bus, the trans is mainly controller by its controller and the engine by its controller. It is important that the controller match the unit that it controls in terms of the model and the year of manufacture. And the trans controller also is programmable and sometimes needs to become acquainted with the trans to which it is mated and/or given an updated program from the dealer the he gets from Chrysler.
But I suspect that your problem is in the trans proper, though it could be the trans control module but I would never replace a controller without proof that it was the problem. The controllers have the ability to recognize malfunctions and record them in their memory as a fault code number. A reader that plugs into a jack under the dash is necessary to connect to the controller memory and get the codes readout, if any. Here is my "boiler plate" essay on this situation:
"It sounds like your electronically controlled transaxle has detected some problem with the unit and in order to avoid any unnecessary damage has gone into "limp-in" mode which means it won't shift out of 2nd gear. It allows the car to be driven at moderate speed to a garage for analysis. The transmission controller logs the problem as a two digit number stored in its memory. The transmission controller does not have a 'self-read' capability as does the engine controller so you can't use the ignition switch to get its fault codes.
The dealer or a competent transmission shop should have a readout unit to find out what the code number is and from that they can make some conclusions about whether the trans can be repaired without being removed from the car (for example a electrical or hydrualic pressure problem) OR if some mechanical damage is involved (but if that is suggested I would follow-up a "mechanical damage" diagnosis by dropping the oil pans and looking for debris to be present or not) which if true would require a pretty expensive rebuild, I am sorry to say. No debris in the pans would suggest the possibility of an hydraulic problem only.
So that is my best advice, go to a dealer/independent and ask for a diagnostic readout of the transmission controller and an estimate for repairs. Get the code number(s), and if you like, write back with a 'follow-up' question to me and we can compare what you are told with what the shop manual says is the problem of that code, and then decide if you are getting the correct advice. You don't have to give them a blank check, just ask for a diagnostic readout, the code numbers and the repair estimate. It will cost something to get that done (should be well under $100), but the more information you have before going forward the better. I would not go to a franchise-type (AAMCO) transmission shop, but rather an independent with a good reputation or a Chrysler dealer. The place has to have a code reader with the adapter plug that mates with the Chrysler-type transmission readout plug. So inquire whether that is true, if you don't go to a dealer shop. If you go ahead with the repair, the cost of the diagnosis is often credited against the repair cost. But don't rush to judgement because a total rebuild costs about $1,500 so you don't want to authorize that unless it is the only possibility."
On the battery question, it is not likely that any damage was done unless the posts were reversed which would possibly damage alot of electronics and that would be experienced not only in the trans but also in the engine function.
The one experience you mentioned of the trans shifting properly one time is not unusual, for if you disconnect the trans controller is will drop out of 'limp in', but then when it sensesthe old fault it will revert to limp in mode again. So there is something wrong in the transmission.
So find out what the code is and what their interpretation of the problem is and how much they would charge to repair it. Then write me back with all that info.
Roland
