That might be worth the few minutes...Get a can of contact cleaner that is safe for plastics. Disconnect the TCM (I believe it is an 8mm socket) harness. Pull the harness off, and spray the harness down to remove any debris. Take a few minutes to let the harness dry, and inspect the connections. If possible, remove the cover that covers the back of the harness, and look for a possible pinched or broken wire.
I will try to get a copy of those two pages for you ASAP. I am waiting for a part to fix my server so I can print and scan again.
Just a quick update. I had the car back in the trans shop for a week while i was laid up with surgery. It had been perfoming 100% normal in
3 but if i put it in D it would go into limp. The trans shop worked on it and when I went to pick it up (free of charge as its under warranty) they smiled and said drive it a few weeks and let us know how it goes and we will tell you what we did. Well I drove it for 3 weeks and no problems and no limp! I was amazed so I called back and they told me that all they had done was unhook the computer and spray a ton of contact cleaner on the cable contacts. I was floored but happy, until yesterday, it went into limp again. So now I'm trying to decide what to do next. I may order the harness from Dodge or I may try some contact enhancer like DeOxIt Gold or
Hate to jump in so late, but did you try changing the "saftey shut down relay" AKA the "EATX relay"? Worn or corroded contacts on this relay will cause intermittent limp in as was told to me by a Dodge service tech when I had the same problem you have. He said that's the first thing he would change in a "Mystery Scenario" and there's a fair chance it would fix the problem. They cost about 20 bucks.
which gets great reccomendations. Aha, so that's the stuff. When I wrote my last post above I mentioned something that cost $22. Well, that stuff from Napa is Stabilant 22A, so I probably confused the 22 with the numbers in the title for the cost. About the cost, it's now $72.
20 years ago, when I ran across this stuff, it was around $25. Must be good stuff to last all these years, that's a lot of years and no name change. According to the web site,
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it was product of the year in Jerry Pournelle's column for Byte magazine, in 1985.
I guess the price was too high. I do use isopropyl alcohol a lot and Stabilant 22A is 80% alcohol and 20% their special chemical. It's spelled out in their MSDS sheet.
Did the tranny shop say what specifically they used to clean the contact cleaners? The above expensive stuff or Radio Shack or what?
Did they try what the next post suggested?
What do you think? A marginal connection or component or resistor that meets specs when you lower the connectivity resistance. Have you tried the suggestion from the next post about the safety limp mode system?
I use the DeoxIT stuff. So much easier to use than Stabilant and for me works so much better. Plus there are many convenient applicators to use. Many of the auto companies spec it in - as the ONLY thing to use. Good enough for me. I don't use anything else. Another plus - cost much less than Stabilant.
Well time to ressurect this thread even though I would like to burry the car.
In October the shop rebuilt the transmission for the 4th time and then they put their foot down and told me they wanted to find the problem and didnt want to release the car to me till they did so. After a few days they called and said it needed a new TCU so I went and picked the core up from them and took it to Dodge and obtained a replacement. After the trans shop installed the new TCU the car was fine until yesterday.
Yesterday I am on my way home on the freeway and the speedometer starts dropping speed and then jumping back up while I was maintaining a constant speed. When I took my normal offramp to come home it dropped into limp and stayed there despite shutting the car off and trying to drive it and also trying to drive it in 3rd which had worked prior to the last in shop repair.
So I took a guess that the output speed sensor had crapped out and got a new Bosch unit and put it in, no change. When you drive it the speedometer needle is all over the map and it stays in limp.
Did Dodge keep the core of the TCU? Maybe you can swap it back in as a test?
Sounds like a bad electrical connector somewhere to me. Take apart all the connectors and if there's water in any of them then spray WD40 in them. Go to Lowes and they sella bottle of electrical conductive grease, put a tiny dab of this on each contact and reassemble the connectors. Do this with every electrical contact on the transmission and harness to the TCU.
On this transmission the fluid lines are above the sensors and fluid leaks will come down right on the sensors, and soften the rubber that holds the contacts. The contact design itself in the sensor also sucks rocks.
Also make sure your body grounds are good, the TCU is grounded, etc.
I agree with your diagnosis of the output speed sensor this time around. I've never used Bosch sensors since I had trouble with Bosch plugs once so stay away from their components unless there is no other alternative. You say the trans has been rebuilt 4 times, but did it actually require this action each time or is this just showing the limitations of the shop you have chosen?
Some suggestions to consider:
Weak/dying battery, resistive electrical connections, bad/poor ground to TCU, bad connector at the output speed sensor, defective wiring to the sensor, etc.
The codes have been worthless in the past always pointing to a bad speed sensor and there were both replaced several times and their harness gone over. That said I would normally have gotten the codes pulled in short order but the car crudded out on me on friday on the way home from work and I never had a chance to get it to the shop before they closed for the weekend.
Yep, was something like a $85 core charge besides the chip directly under the inspection plug on the cover was cooked as was all the potting material over the chip.
I may try this again, its been done numerous times, the last time I used DeOxIt and their gold contact enhancer. Didnt help at all.
Thanks Ted, this transmission is an example of how not to design a transmission from the cruddy sensors, to the sheer number of TSB's to the very sub par electronics...
Grounds are good, and there is a ground directly from the bellhousing directly to the "Jump Start" negative terminal.
On Sun, 31 Dec 2006 17:14:12 +0000, Bob Shuman wrote:
Not sure if its their limitation or just the fact that the bloody thing is so intermittent when it fails and the computer diag is worthless well.... I dunno the shop has tried I will give them that.
All I can think is a wiring gremlin, but Dodge wasnt ever able to find it either. All said and done this transmission failure has cost me more than the car did. I filed a NHTSA report on this last night. Here is the body of it.
Your Confirmation number (ODI Number) is: 10177406
Complaint Information Description : Purchased vehicle with clean CARFAX record in Feb 06 with 75k Miles. At 81K miles transmission started going into limp mode(slams into second gear regardless of vehicle speed). Took car to dealership for diagnostic. They stated the input and output speed sensors were failing according to the computer. I replaced them. A week later the transmission fully failed. Towed to a reputable transmission chain store. They fully rebuilt the mechanicals of transmission and replaced the speed sensors again. As I drove home the transmission returned to limp mode. Returned to shop. They test drove it and second gear clutches burned up. They rebuilt it again and also replaced valve body and solenoid pack. I drove the car for a month before it again started limping. Took the car to another dealership for diagnosis. They blamed the shop and stated they couldn't do anything for me but upgrade the flash in the transmission computer. The computer diagnostics could not reveal why the computer was putting the car in limp. Returned car to previous transmission shop for yet another rebuild. Drove car 2 months before it again started limping. Returned car to trans shop, they rebuilt it again. Still couldn't find concrete cause, replaced valve body again, had me buy replacement transmission computer from Dodge, this fixed it for another 2 months. yesterday it again started going into limp. There is 200 miles remaining in the 12,000 mile rebuild warranty from the first rebuild so it will be in the shop for the 5th time in less than a year.
If the computer keeps throwing a code for the speed sensors you are going to have to put a oscilloscope on the speed sensor output and check it to see that your getting a solid signal. Then run the vehicle on the highway for an hour and come back to the garage and let it idle for 20-30 minutes to get it really good and hot, and then recheck both input and output speed sensors output with the scope.
It's not just the design, it's the implementation. For example, take the input speed sensors. The original ones were brass. Later the vendor that made then switched to plastic. Lots more sensor failure complaints then. The theory is the plastic does not conduct heat into the body of the transmission as readily, so the chip inside the sensor fails due to overheating.
Well, you MAY have gotten a bad replacement sensor (Bosch is all over the map in terms of quality these days). Or, more likely, its a wiring problem somewhere in the wires that go from the sensor to the computer.
The trans didnt fail taking it to the shop nor for the shop, he thinks I fixed it with the replacement sensor or perhaps it was just a bad connection. Supposedly there is a TSB on a replacement connector and I half recall seeing it but cant remember if its to replace the cruddy
95 connector or to upgrade the 95 connector to the 96/97 or later connector. Anyone recall?
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