DodgeTalk Forum banner

1 - 20 of 22 Posts

·
Registered
Joined
·
18 Posts
Discussion Starter #1
Hi guys; I'm stranded in Florida, 1100 miles from home and my transmission is stuck in limp mode, it's showing two codes, P0750, shift solenoid A and P0700, info. I took it to AAMCO because they were within walking distance from where I'm staying. They've had it for 44 days and still haven't found the problem. They've done everything they know to do and it still isn't fixed. They replaced the ECM, twice, the TCM, twice, they checked the shift valve block, electrical and mechanical then replaced it just in case, the speed sensor checked okay, speedometer works, they checked the wiring both physically and electrically. Transmission made no noises and it was working fine when I shut it off the night before, next morning it wouldn't shift. I would have to have to try to drive it home at 35mph. What's left to check?
 

·
Registered
Joined
·
18 Posts
Discussion Starter #2
Hi guys; I'm stranded in Florida, 1100 miles from home and my transmission is stuck in limp mode, it's showing two codes, P0750, shift solenoid A and P0700, info. I took it to AAMCO because they were within walking distance from where I'm staying. They've had it for 44 days and still haven't found the problem. They've done everything they know to do and it still isn't fixed. They replaced the ECM, twice, the TCM, twice, they checked the shift valve block, electrical and mechanical then replaced it just in case, the speed sensor checked okay, speedometer works, they checked the wiring both physically and electrically. Transmission made no noises and it was working fine when I shut it off the night before, next morning it wouldn't shift. I would have to have to try to drive it home at 35mph. What's left to check?
I forgot to mention that it is an 02' Grand Caravan 3.3, 4 speed Sport.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #3
I thought that it could be the transmission itself but after clearing the codes when I turn on the key but don't yet start the car the codes come back and I hear the DING sound indicating that the check engine light should be on but it's not.
 

·
Registered
Joined
·
626 Posts
I'm not sure how much help I can be, but I'm going to offer what I can. I discovered I still have transmission wiring diagrams for an 03 and that should work for your 02. I don't have much else in terms of service info. I'll have to make some assumptions and educated guesses, but I think they'll be close enough.

If you're 100% certain that the code P0750 will set before you even start the van no matter how many times you erase the codes, then I'm fairly confident that somebody has been getting outsmarted by a bad wire or connection. Since a lot of components have been replaced more than once, that tends to suggest something was overlooked in the wiring. If they've been relying on Dorman or Cardone remanufactured parts, I wouldn't be surprised if they did get two bad PCM's or TCM's in a row. For now, I still want to focus on the copper strands.

The way I would expect the TCM to self test is by monitoring voltage at the end of the solenoid A circuit. There's a secondary sensing circuit that is also monitored. Both of these circuits have full time, key on power from the same fuse. Both are ground side switched, both are monitored by the TCM, but the ground for the solenoid is electronically controlled while the sensing circuit is physically grounded by transmission fluid pressure. This the TCM's way to verify that solenoid A works mechanically just as much as it does electrically. All they do with the sensing circuit is split a ground circuit behind a resistor so the TCM can tell when the physical switch is closed.

When the key is turned on, the TCM should immediately see battery voltage from the solenoid A circuit. I'm not sure exactly what voltage it needs to see on the sensing circuit because I'm not sure how they terminate the circuit inside the TCM when the physical switch is open. I would bet the voltage should be close to battery voltage though. In saying that, I would also bet it should only see something close to zero volts once that mechanical switch is closed during normal operation.

Assuming the code sets immediately, you're likely already down to only three wires you really need to test. Maybe five depending on the first one I tell you about. (Most of the testing I tell you about will mostly be key on, engine off testing procecures.) There's a YEL/ORG wire that is the common power wire for all the transmission solenoids and their sensing circuits. It also branches out two more wires that sends power to the TCM. Since it's the TCM's job to tell you about the code you're chasing and it's only reporting one, I'm inclined to believe that wire is not a problem. I would check it with a voltmeter for battery voltage on the YEL/ORG wire at the solenoid pack just to cover the bases. The next is a DK GRN/WT wire and it's the ground control circuit for solenoid A. (If you look at the diagram, they call it the low/reverse solenoid.) With KOEO, that wire should be showing battery voltage at the TCM as well. That last wire is YEL/TAN and it's the ground side of the sensing circuit. Like I said before, I expect that one to also be somewhere in the neighborhood of battery voltage. As long as the key is on, the power wire should always have battery voltage, the solenoid A wire should have something close to 0 volts only when the TCM commands the solenoid on. The sensing circuit should follow suit.

I know they said they checked the wiring, but hearing that from others has never got my hopes up. I'm not sure you should mention this post to whoever is working on your van. A lot of mechanics are quick to get defensive or butt hurt if you question their Ohm meter. It's dumb because this is an easy area to get tunnel vision or overlook something simple in the complexity. I misread the diagram myself and had to rewrite most of this post. Oh well. In absense of having a van in front of me and not having known good voltage specs, I'm going to spout off a little more about what else I'd be looking for anyway.

If you need a little more understanding, the testing I mentioned above is called voltage drop testing. Much of the testing is Key On, Engine Off and my voltmeter negative lead is clamped to battery ground and I'm using the other lead with a fine tip back probe. When I'm in there and I'm back probing wires, I might gently wiggle the harness between the solenoid pack and the TCM to see if the voltage stays steady. Fluctuations that turn up might help point to a break in a wire that's still making intermittent contact. If I'm just not done being uptight or uncertain about the sensing circuit, I'd turn the key off, disconnect the TCM connector and depin the YL/TN wire from terminal 50. I'd plug the TCM back in, turn my key back on, and look for battery voltage at the end of the wire I just depinned. In this state,battery voltage is all you should see.

If my assumptions are wrong and/or voltages don't offer solid answers, then its time to look at pins & terminals for loose fit or corrosion. The next move is to turn the key off and disconnect the TCM connector. Try sliding your depinned terminal on to its appropriate pin in the TCM. Make sure it's got good drag and feels snug to the pin. Before repinning that wire, change the multimeter to Ohms and gently attach the free meter lead to the terminal. Move the other lead to pin 20 on the TCM connector if you can front probe it without damaging it. Gently wiggle the wire near the terminals itself and make sure it maintains good continuity. (Ford & GM usually burn me on this where there will be a break in the wire right at the terminal just behind the crimp that you can't see. I don't see why Dodge can't be just as disappointing.) If it turns out it's just a loose terminal to the pin, clean it and compress it where you can to put that drag back into it. Repin that end of the wire and repeat this on all ends of the suspect wires.

When testing is going on at the solenoid pack, I'd want to take a good look at the connector while I'm there. Make sure there isn't oil or transmission fluid that somehow managed to leak into it. Make sure everything is clean and dry as the fluid can cause a short if there's enough fluid in it. If corrosion is found in a connector, mating pins need to be checked and the amount of green fuzzy shit found dictates whether cleaning is attempted or a connector gets replaced outright. Mopars are good for green fuzzy shit. I hope that's not the case for you.

There is more I'd like to suggest, but it would require a good scan tool, service info, and probably a good automotive scope to cover my ass. I no longer have access to any of that goodness. Now that I think about it, they don't matter anyway. I can't even see your Caravan from here. I did, at least, attach the diagram I used to fomulate my plan. Don't mind the yellow highlighter on the diagram. That's part of where I was misreading it myself.

Good Luck.


Caravan transmission cct diag for Florida.jpeg
 

Attachments

·
Registered
Joined
·
18 Posts
Discussion Starter #5
Day 45, I printed out your research (above) and gave it to the manager and told him that I was getting desperate to get back home so we'll see what happens.
Thank you very much for your time and research.

Okay, just to recap what has been done, the ECM was changed 2 times, the first one changed was definitely defective so a second one was ordered to replace it.

The TCM was changed 2 times because it was suspected that the first one might have been defective. ????????

A new fuse/relay block was installed just in case and the wiring involved was by-passed with jumpers. The wiring involved was load tested as well as continuity, and connections were visually and physically inspected.

The solenoid pack was replaced.

Transmission fluid was replaced about 40,000 miles back with ATF+4 and is still a good bright color and at the proper level.

Codes P0750 and P0700 were repeatedly cleared throughout the testing and the battery ground connection was removed but the codes returned when the key was turned on but the Van was not started.

I've got less than a week until I have to get out of here, even if it's with a rental truck and a car carrier.
 

·
Registered
Joined
·
626 Posts
One thing I forgot to suggest was testing powers and grounds of the TCM itself. I know I mentioned I wasn't so concerned with two of those power wires, but considering the range of everything just not going right, I'd want to isolate the TCM connector and load test the power & ground circuits with a headlight and wiggle harnesses. It's a little overkill, but it does eliminate any uncertainty.
 

·
Registered
Joined
·
626 Posts
I found a case study for another 02 Caravan that was having different transmission circuit problems and I learned a little more that might help. It did prove me wrong in a couple ways as well. The case study showed that the TCM will cut power to these circuits after a failed self test when the key is cycled on. It was said this is a defense strategy to force the transmission into limp mode. I initially had a hard time rationalizing it, but the guy providing the case study proved his point in a video. (I'm wondering if this might also be normal to simply not power these circuits after a self test until the engine is running anway.) At any rate, the guys working on your van might already know they'd need to jumper the 30-87 pins at the EATX relay for much of the voltage drop testing I have in mind. Otherwise, a lot of what I recommended is useless. They could also try their testing Key On, Engine Running and verify for themselves whether or not I'm providing useful information.

I sometimes wonder if the other two branches of the YEL/ORG wire I wasn't so concerned about might need more attention than I thought. (Pins 16 & 17 at the TCM.) If it wouldn't hurt anybody's feelings to try it, they'd just need voltage drop testing for battery voltage like everything else. The case study said they're probably sensing circuits and it makes no sense to branch two circuits like that just for sensing when it can already do the same job through any of the shift solenoids. But, I had this 2014 Ford Focus kick my ass once with a no comm fault and a comatose PCM caused by a broken coil power wire. I reread the service info a few times and never once saw it ask me to diagnose any coil circuit for a PCM that won't wake up. A Ford tech told me it was another "wake up" circuit for the PCM. I still don't believe it, but it did lead to the root problem. That nugget of my history makes me think that since the so called sense circuits at pins 16 & 17 at least share power with the solenoid pack, they might be worth some testing.

Sorry to keep editing, adding, and correcting. But if those guys are taking anything I've suggested to heart, I owe it to them to correct myself.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #10
I was just over there on the chance that they might be there even though they are closed on Saturday and Sunday but no one was there yet, I'll check again later today.

At this point it has to be something simple, I'm betting on either a bad ground or corrosion or some kind.

I've only got five days left and need to leave.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #11
I've been over to AAMCO several times today and one thing I'm concerned about is that they have had the ignition key on but the engine not running.

I know from experience that, that will screw up the ECM because it happened to me and I read somewhere a warning to not leave it on for more than 20-30 seconds. I hope they haven't damaged the reconditioned ECM. Do you know if this is true?
 

·
Registered
Joined
·
626 Posts
This is the first time I've ever heard of a car smoking a PCM for leaving the key on. If a shop told you leaving the key on was the reason a PCM got smoked, stop going to that shop.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #13
No, no, it wasn't the AAMCO shop guys, it happened to me before, it was a few years back. And then I read about somewhere and I said yeah that happened to me.

What happened was, I got in the van and turned it on to start it but got distracted and called away for a few minutes but neglected to turn it off, when I came back the windshield wipers were slowly running and the van didn't act right. Later it quit all together and I had to have it towed to the Dodge dealer for repairs, they replaced the ECM and it was fine again. Costly.
 

·
Registered
Joined
·
626 Posts
I still wouldn't blame leaving the key on. I believe it was entirely coincidental that it failed when it did. It's easy to assume there was a direct cause & effect under the circumstances. It has my curiosity, though. Did they happen to find a bad battery or any other wiring problems at the same time?
 

·
Registered
Joined
·
18 Posts
Discussion Starter #15
No, not that I'm aware of.

A third technician has been working on it most of the day
He said he was under pressure to find and fix the problem, hope he does.
 

·
Registered
Joined
·
15 Posts
Hi guys; I'm stranded in Florida, 1100 miles from home and my transmission is stuck in limp mode, it's showing two codes, P0750, shift solenoid A and P0700, info. I took it to AAMCO because they were within walking distance from where I'm staying. They've had it for 44 days and still haven't found the problem. They've done everything they know to do and it still isn't fixed. They replaced the ECM, twice, the TCM, twice, they checked the shift valve block, electrical and mechanical then replaced it just in case, the speed sensor checked okay, speedometer works, they checked the wiring both physically and electrically. Transmission made no noises and it was working fine when I shut it off the night before, next morning it wouldn't shift. I would have to have to try to drive it home at 35mph. What's left to check?
Hi guys; I'm stranded in Florida, 1100 miles from home and my transmission is stuck in limp mode, it's showing two codes, P0750, shift solenoid A and P0700, info. I took it to AAMCO because they were within walking distance from where I'm staying. They've had it for 44 days and still haven't found the problem. They've done everything they know to do and it still isn't fixed. They replaced the ECM, twice, the TCM, twice, they checked the shift valve block, electrical and mechanical then replaced it just in case, the speed sensor checked okay, speedometer works, they checked the wiring both physically and electrically. Transmission made no noises and it was working fine when I shut it off the night before, next morning it wouldn't shift. I would have to have to try to drive it home at 35mph. What's left to check?
Hello there, just reading your post. Am I understanding the transmission won't shift out of 1st? If that's the prob. I had the same issue. The problem is relatively easy to fix and not too expensive. It's a common dodge issue with governor pressure solenoid and sensor. You need to replace both, they work together. You will have to drop trans. Pan and take off the module where these are installed. Replace them (easy), and really install module. Fill with oil and good to go. Hope this helps.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #17
Imagine with me now; is the transmission circuits in a box so to speak? Or can other circuits outside of the transmission control
Hello there, just reading your post. Am I understanding the transmission won't shift out of 1st? If that's the prob. I had the same issue. The problem is relatively easy to fix and not too expensive. It's a common dodge issue with governor pressure solenoid and sensor. You need to replace both, they work together. You will have to drop trans. Pan and take off the module where these are installed. Replace them (easy), and really install module. Fill with oil and good to go. Hope this helps.
I believe it defaults to 2nd gear because
circuits cause the computer to go into limp mode? For example, a defective temperature sensor or a defective air/file mixture sensor or whatever? They (AAMCO) have checked, double checked and triple checked everything they can think of. Three technician's have gone over it throughly and still no progress.
I'm getting desperate.
Hello there, just reading your post. Am I understanding the transmission won't shift out of 1st? If that's the prob. I had the same issue. The problem is relatively easy to fix and not too expensive. It's a common dodge issue with governor pressure solenoid and sensor. You need to replace both, they work together. You will have to drop trans. Pan and take off the module where these are installed. Replace them (easy), and really install module. Fill with oil and good to go. Hope this helps.
I believe the transmission defaults to 2nd gear in limp mode, 35mph at 2500rpm and 40mph at 3000rpm which is terrible on fuel mileage. Anyway I will mention it to them,






thanks. They have tried everything else.

I just got back from AAMCO and Shawn said that all electronics and sensors are on the outside of the 41te transmission, no reason to open it up. Their putting a fourth technician on it today and I'm supposed to be out of here today.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #18
Well I have accepted the fact that I may be here for a long time yet and in the end I may have to rent a truck and a car tow dolly to get home. I have stopped going over to AAMCO because I have no more suggestions to make and I'm sure they don't appreciate it anyway, when they get it fixed if ever, they will call me. I will loose may place to stay on the 27th of April and I will be forced to leave fixed or not.
I have gone over all I can think of that might cause the problem but I am totally stumped as are the guys at AAMCO.
 

·
Registered
Joined
·
626 Posts
Well I have accepted the fact that I may be here for a long time yet and in the end I may have to rent a truck and a car tow dolly to get home. I have stopped going over to AAMCO because I have no more suggestions to make and I'm sure they don't appreciate it anyway, when they get it fixed if ever, they will call me. I will loose may place to stay on the 27th of April and I will be forced to leave fixed or not.
I have gone over all I can think of that might cause the problem but I am totally stumped as are the guys at AAMCO.
This may be the right time to simply forfeit the van to AAMCO. It's 19 years old and I'd think you're poised to spend many hundreds of dollars to get it 1100 miles away. From a point like Tallahassee alone, that puts you well within a radius that makes me wonder if it's a heavily rusted 19 year old Caravan. There's no resale in missing body parts from rust. Then once you get it home, you have to spend who knows how many hundreds more to have it fixed for real. This begs the question: Is AAMCO going to charge for their work? If you're eating parts & labor despite their failure to repair it, I could see the solenoid pack, PCM, TCM, and their programming costing you a thousand if you're really really really lucky. For what that's worth, the shop might only be covering their cost at best.

I don't have all the angles covered here, but I'd hope you can see where you might very well spend more than it's worth in a couple different ways. If you can get a better sense of what you're going to spend and it exceeds $2000 before an actual repair is done, I'd expect that to be more than what the van is worth already. Let's pretend the next shop does fix it, but they find out the last shop's new parts are faulty. (I warned you before about Dorman and Cardone remanufactured parts. They really could have shipped you multiple defective modules.) If you have to buy yet another PCM and TCM, I fear for you losing $3000-$3500 by the time it's all said and done. I think I'd rather buy a plane ticket home and spend $3500 on something that already goes down the road.

Since I can't speak for the quality of the people at the shop you're dealing with, I think giving up the vehicle and mailing them the title is fair enough compensation for their time if you feel they've made a legitimate effort to fix it. If you think they're hacks, ask them to reinstall your old parts and ask them to pay for the rental equipment you need to get the van home. I normally wouldn't suggest something so severe. But they have fired the pricy parts cannon multiple times to no avail and have also literally left you stranded. They're not going to pay you for the rentals, but it might be good leverage to get them to the first scenario where they keep the van and you mail them the title. Get an agreement down in print either way. (In my mind, there should be no scenario where you have to open your wallet for AAMCO for any reason if you leave the van behind.) If you're bringing the van home anyway, you still want the original parts back in the van and, ideally, AAMCO returns the new parts and fights with its vendors to get refunded instead of billing you for their dead ends. The benefit of having your original parts reinstalled helps the next tech approach their diag with less contingencies to think about.

Since I can't offer you a real solution, this is the best I can think of to cut your losses and get home. Hope this helps.
 

·
Registered
Joined
·
18 Posts
Discussion Starter #20
In the beginning of this escapade I took the van to AAMCO because they were within walking distance, I paid them $600.00 down payment (deposit) for repairs. They called me about 2 weeks later and said it was ready to go, so I walked over there and paid the final bill in full, a total of $1150.00 and change. They said that the ECM had been the problem and they replaced it. So they gave me the key and I left. I drove down the street to get gas but the transmission still would not upshift so I immediately took it back to AAMCO,
NOW IT'S WARRANTY or it should be.
AAMCO is a national chain company and I should be able to have it worked on under warranty up in Indianapolis.

In 12 days I absolutely have to leave Venice, Florida, I will no longer have a place to stay. So if they don't get it fixed in 10 days I will be forced to rent a small truck, about $671.00 and a car hauler dolly, about $61.00 plus taxes, insurance and gas to load up furniture and drive back to Indiana.

I have tried to be patient and understanding because I am a retired mechanic and I know it can be frustrating on a problem like this, but, I'm up against a wall here now and I have to make a choice.

I know that the van is not worth much in resale value, maybe a $100.00, but it's worth much more to me and I will get it fixed some how.

Again, thanks for your help, I do appreciate it.
 
1 - 20 of 22 Posts
Top