Transmission control module location

It is on the right inner fender its right up on top, with three rectangular plugs. It is just a few inches forward of the right hood hinge.

What kind of problem are you trying to solve?

Check out the diagrams (Below). Cheers

Lot of times it would be running fine on the highway and then it would slip into neutral and then go back Into second gear and stay locked into limp in mode. Takes a long time to shift into gear if it rained or was cold. Then one day it was over heating and spewing some kind of liquid on passengers side of motor. Then car just would not shift again into any gears and now it makes a high pitched winning noise in all gears. We are broke and have our own family, money is tight. So we are trying to fix this on our own. Cannot afford to take it to the shop and it is our only way around. We have been stuck on our feet for three months now and desperate to fix this. I have done a lot of research and I keep getting led back to its the TCM gone bad. So I have saved the money and am fixing to order the part, but before I spent money we do not really have I wanted to reach out to some one who might know more . I am also planning on getting a new filter for the transmission pump the kit with a gasket and o-ring and also going to replace the fluid as well. Please help me. Am I on the right track or am I wrong? Do you know maybe what is up with our car? Any advice is much appreciated

The first thing to try to do is determine exactly what is taking place when it drops into limp mode. Most commonly that is during an up-shift to a higher gear. When the clutch plates are worn to the end of their life, excessive slippage takes place, and the computer detects that before final full lock-up occurs. You can work around that by accelerating a little harder than normal, then letting up on the accelerator pedal for a few seconds to let the next higher clutch pack lock up solidly under no load. Once firmly engaged, then accelerate the same way to the next gear. That is not fixing anything. It is just helping you get by for another few thousand miles, but the real solution is to rebuild the transmission.

If it ever goes into limp mode right away, before you even start moving, it is almost always due to a sensor or wiring/connector terminal problem. The computer detected that defect when no clutch pack is engaged yet.

There are two things you can do first, but it involves a mechanic with a scanner that can access the transmission computer. Definitely do not unplug the computer or disconnect the battery. Either of those will lose power to the computer which will erase its valuable stored data. The first thing your mechanic must do is to read and record the diagnostic fault codes. Those will give us an idea of where to start the diagnosis. The next is to read the "Clutch Volume Index, (CVI). That is a set of four numbers corresponding to the volume of fluid it takes to apply each of the four clutch packs. An experienced transmission specialist can tell by those how much life is left in the transmission. You may want to visit a transmission specialty shop for this. Reading all this data only takes a few minutes, but you need someone who knows how to interpret it.

I have a 1993 Dynasty, twin to your model, and I have a Chrysler DRB3 scanner for all of my vehicles, so I know how to retrieve the data, but not how to interpret the CVI numbers.

There has been times the car would start out like this, stuck in low gear we would not ever get to make it out of town, unless we wanted to drive thirty mph the whole way. How do I get it to a mechanic? And yes, most of the time it was on the high way going into higher gear so we could drive seventy mph not thirty mph it would shift okay into high gear but then shortly down shift. As soon a we would slow down there it would go and downshift again.

And when it did this either it just would not shift into higher gear or when we would be driving it would down shift and no matter if we sped up or slowed down it would stay there. Now if we stopped, shut car off or this may sound crazy but if we drove over some bumps it would go ahead and shift.

I do not have a way to get it to a mechanic. I do not have money for a tow.

Could it not be from the TCM?

The purpose of limp mode is to keep it in second gear specifically so you can drive slowly to a repair shop without needing a tow truck. It will never come out of limp mode on its own while you are driving. The only way to do that is to turn the ignition switch off, then restart the engine. If it is coming out of limp mode while you are driving, that would point to an intermittent bad connection causing power to be lost to the Transmission Computer. That is where knowing the diagnostic fault code numbers is helpful. Without that information, there is no way to know which circuit or system needs to be diagnosed.

Thank you. I am going to try replacing TCM.

If you think that is it without diagnosing anything first, get a used one from a salvage yard. It will plug right in with no need for any kind of programming to your car. Go by the application, not the part number. There were many revisions to these computers, and each time one was sent in for repair, it got all the updates and a new part number.

Used one off eBay. Pulled off a running vehicle.

Thank you.

Did it fix the problem?

Will not know until I get the part.

About to order the TCM. Is there a picture or diagram or link you could show me the location of the TCM on our car?

Yes, on the first post (above) in the diagrams below click to enlarge it.

I finally figured out the problem. If you look at that diagram way up at the beginning, it is wrong. It is a mirror image of the correct module location. It shows the receiver/drier for the AC system right in front of the module, but that is on the passenger side, just like where I said the module lives. It is right in front of the passenger side hood hinge, bolted to the inner fender.

Thank you! I am fixing to order the part and I will let you know how it turned out.

Be aware there is a relearn period after power is lost for this computer. It has to learn the volume in CC's of fluid it takes to apply each of the four clutch packs. That is the "clutch volume index", CVI I mentioned earlier. By knowing that, when a clutch pack has badly-worn plates, it takes more fluid to apply that clutch, and that takes more time. It will update and modify its shift schedules to engage third gear, for example, then wait a fuzz longer than normal before releasing second gear. That longer overlap results in a nice clean, solid shift like when it was new, right up to the time it cannot update any further, then the slippage occurs and it goes to limp mode. The disadvantage to this is you do not get to feel that slippage as "engine runaway" like we had years ago before these computer controls. We used to get a good two or three years of mushy shifts as a warning that a transmission rebuild was in our future. Not any more.

We were always told at the Chrysler schools that the shifts could be real sloppy or soft, or harsh like those of an older muscle car, for the first two miles or about a dozen up-shift cycles, but in actual practice, it was rare to observe anything unusual at all. This does not apply only to replacing the computer. It applies to any Chrysler model with a Transmission Computer when the battery is disconnected to replace it or for any other routine service. We were always told that if the work we performed did not require a test drive, we were to do one anyway to do that relearn for customer satisfaction. That directive went away over the years because it just was not necessary. My reason for mentioning this is I am worried you have worn clutch packs and the new computer is not going to solve anything. I hope I am wrong, and if I am, I do not want you to be concerned if the shifting does not feel right, right away. If it no longer goes into limp mode, drive the car a few miles before evaluating the shift quality.

Besides all the different part numbers these computers can have, some have finned heat sinks on the side and some do not. My 1993 Dynasty did not have the heat sink, and when I mentioned one of the ten common "irritants" about shift quality, I learned there was updated software that could be installed, but only those computers with the heat sink could be "flashed" with that new software. I got a new computer with the heat sink, under warranty, then I put the new software in it at the dealership I worked for. Unfortunately it did not change anything, but compared to some cars I have driven, mine has nothing to whine and snivel about.

Thank you! I will keep this in mind, especially if this does not work. Is it expensive to fix?

Thank you for all your help and advice and will post updates as soon as we start work on our car. There was also a high pitched whining that had started the same day it slipped completely. It spewed some fluid that night and now makes a whining noise. I am replacing transmission filter and fluid during all this as well. Any ideas as to if this new noise had anything to do with our transmission slipping?

Yes, if the filter is plugged the transmission will lose hydraulic pressure which will cause the transmission to slip. This guide will give you an idea on how to service the unit:

https://www.2carpros.com/articles/how-to-service-an-automatic-transmission

Please let us know what happens.

Cheers, Ken

Thanks!

Is there an o-ring holding the filter that I am going to have to replace? I do not have much money and I do not want get out there and need more than what I have got. So will the filter kit come with all I need?

Filters always come with o-rings and gaskets as needed. You are going to have the A604 4-speed transmission. The filter for that has a tube on top that plugs into a hole in the valve body. The o-ring will already be on it.

Chrysler never used a gasket for the pan or rear cover. If your filter comes with a cork gasket, go ahead and use it if you want, but do not over-tighten the pan bolts. That can split the gasket, then it will leak. Fiber gaskets are a little more forgiving, but you still want to be careful when tightening the bolts. Hand-tight with a quarter-inch ratchet is fine.

If the filter does not come with a gasket, or if you want to do the job the way we do it at the dealership, scrub all the old gasket material off the pan and the bottom of the transmission, then apply a bead of gasket sealant to the pan. Now is when the job gets a little tricky. The pan sits at a pretty steep angle. In the middle of the rear edge you will see fluid dripping down slowly. That is coming from the passages and clutch packs and will still be dripping days from now. That surface must be clean and dry before the sealant hits it

Chrysler has two gasket sealers, one is black and one is gray. Other manufacturers have their own versions, and there are lots of different kinds at the auto parts stores that are just as good. I am only describing the Chrysler products because I am very familiar with them and use them all the time.

The black sealant stays a little more rubbery and flexible when it has cured, but it absolutely will not bond or seal through a film of oil or transmission fluid. Some of us will wash the dripping fluid off with Brake Parts Cleaner and a rag, then have a helper standing by with the pan with the sealant already on it, to slap it on before the dripping resumes. You may get up to five seconds to do that. It is okay when the fluid runs over the sealant after the pan is in place. You just need it in place before fluid gets on those surfaces where the bond has to occur. You can even pour the new fluid in right away. The sealant cures from the humidity in the air. Transmission fluid will not interfere with that process.

Chrysler's gray sealant cures a little harder and it is harder to scrape off next time, but it is supposed to seal and bond through a light oil film. None of us are willing to risk causing a leak by proving that statement to be true. We still want the surfaces clean and dry. Since I am almost always doing everything by myself, I found that if you stick your finger up onto the hole where that fluid is running down from, you can splash around in there to empty the depressions where that fluid is puddling. Wipe the flange once more with Brake Parts Cleaner and a rag, but now it can take a good fifteen to twenty seconds for that well to fill with fluid before it spills over and starts to run onto the flange again. That gives you a lot more time to get the pan in place and get a couple of bolts started. If you still end up with a leak after that, join the club. That has happened to every experienced transmission specialist at least once.

Here is a link to an article related to this service:

https://www.2carpros.com/articles/how-to-service-an-automatic-transmission

One former coworker used to stuff a rag up into the hole where the fluid was draining from. After a final cleaning of the surface, he had yank the rag out, then have a few extra seconds to get the pan in place. It worked for him, but I had better luck sloshing my finger up in there.

There is no drain plug on this transmission. Leave two bolts in place but backed-out about two turns on the front edge of the pan, then you will need to pry on the edges to break the bond. Have a large drain pan ready. You will get about five quarts of fluid all at once.

I would be more comfortable knowing the clutch volume index numbers before you do this service. If it turns out you need to have the transmission rebuilt, you will be wasting a lot of money on the filter and fluid that are part of the rebuild job.

What kind of transmission fluid is recommended for our car? I do not want to mess it up.

Here is the fluid type. Oil Type, MOPAR ATF+4 Type 9602, Or Equivalent.

I have the TCM, it is a used working one I ordered that is a fit for our vehicle. It came from a auto shop that they pulled from a running vehicle. It is a used one that works.

My question is, will be able to just do the work of replacing it? Or is there other things I have to do when putting this one in? Can you give me the steps I need to do this? Please!

I cannot say thanks enough. It has been so hard to find someone to help us out. My family is very grateful to you all.

No problem that what we are here for :) It should just plug and play. Let us know.

Got the parts, new filter and fluid for transmission. Silenced the high pitched whining, put a working TCM In the car, added new oil for engine. Here is what happened:

Worked beautifully at firs shifted fine. Then we decided okay, how will it do out on the high way? Well last night was eventful had a small amount of trouble getting it to shift into reverse at first which we had been used to this problem, but once it shifted, it ran smooth as ever in town so we took the car out on high way for the first few miles it ran fine. Then with out warning she slipped like never before entirely different. She slipped and there was this overwhelming metal grinding screeching noise it was awful. I have spent so much time on this car. Do you have any of the cheapest options to fix the car. I am looking at having to replace transmission right?

That was the sound of my transmission going bad internally, huh?

Even as we parked it, it was extremely loud.

Yep, it sounds like it has let go unfortunately. When they clog the filter it means something is coming apart. Can you please shoot a quick video with your phone so we can hear the noise? That would be great. You can upload it here with your response so we can be sure?

This video shows a FWD transmission coming out even though it's not the same the procedure is very similar.

https://youtu.be/6N6b5F2ChyE

Please let us know what happens.

Cheers, Ken

No thank you. I do not feel it is worth the money to buy or replace this transmission. However, I do appreciate all of y'all's help in this. I am not going to chance wasting my money on a car that is no longer safe to drive and that will quit on me repeated times. Thank you all very much. My days of investing in a Chrysler's are simply gone. I should have seen this coming. Clogged filter, transmission failing.

Let me suggest a possible alternative. First, if you only hear the noise when the car is moving, there was a common problem with the small lock bolt in the differential breaking, and that allowed the large pin to slide out and hit on the case. Often that caused the case to crack and spill all the transmission fluid on the ground. That will not cause slipping though or a failure to shift.

You might look for a nearby community college with an Automotive program to see if they can help. We were always looking for live vehicles to give the kids real-world experience. We charged ten dollars per hour for how long the job was listed in the "flat rate" guide that most shops use, and we got parts at real good discounts, then marked them up ten percent to form a breakage fund in case we damaged something. The drawbacks are it can take weeks to get your car back, and we only worked on the things we were currently teaching. To do otherwise would take work away from the local employers who hired our graduates. Being a smaller school, we only taught Transmission and Drive Line once a year for eight weeks. We would not do brake work or suspension system repair, for example, in that class.

As another thought, if the body is rust-free, there is a real good market for cars like yours up here in Wisconsin. I have the twin to yours, a 1993 Dynasty with less than 5,000 miles. Quite a few people have offered to buy it. If you decide to list it for sale on Craigslist, list it under northern cities. I am getting ready to head south to look for an 1988 Grand Caravan to replace my rusty one. There are people around here who head south all the time to bring rust-free cars and trucks up here. Usually they just go and look for them, but if they see it in an ad, they will know exactly where to go.