Engine/Transmission (1998.5 - 2002) Auto Trans anomalies

[Joe Mc]

Truck/Trans in Signature.

A few months back I pulled over to take a call, let run in park. About 15 minutes late I finished the call, placed in "D" and something didn't seem quite right. Truck started out in 2nd gear. This has never happened before, I shut down the engine, resetting if you will everything, and then it started out in 1st and shifted normally. Since this time there have been a few other anomalies; I'd take of from a stop and it wouldn't shift out of 1st, I'd turn into a corner in 3rd it would shift down into 2nd (usual) and then not shift out of 2nd. Seems like whatever is going on is easily "reset" by a turn off and back on of the key (engine/electrical systems).

Any ideas help are appreciated.

 

[BigPapa]

I have had similar issues when my speed sensor went bad. Not sure on your 4X4 but on my RWD it is located on the driver side at the rear of the transmission. Takes a pretty large wrench but is no problem to remove and replace in a matter of minutes. The tip of mine has come off twice.

 

[Joe Mc]

Scott,

Thanks for your reply. I know there's a speed sensor in the rear diff, but wasn't aware of one in the trans. Will take a look in the ol` shop manual and see about it. Will let you know what I find out.

Joe

 

[Joe Mc]

After searching on line I found there's an in-put and out-put sensor, which one was your problem?

 

[Joe Mc]

So for the input/output sensor question above; Dodge Shop Manual only shows (or I could only find...) output sensor.

Changed the output speed sensor. Still same thing, acts normal and then whenever & for no particular reason, it won't shift out of first and/or sometimes will start out in second. Pull over shut down and all is well...for a while?

I called the trans builder (Tim Barber out of VA Beach, VA, Pres. of TRE Diesel Performance, Trans is a DTT) and he told me the symptoms (as in the past) point directly towards the Gov Psi Sensor and Solenoid/Transducer. He reminded me that these seem to fail every few years or so. I asked where I can get quality parts in hopes of getting longer than a few years out of these things, which nowadays I only put about 10-15 k miles a year on the truck if that. He recommended locating a local Transtar Industries for quality parts, which I did and picked them up. When I got home and opened the boxes the parts were sealed and had Chrysler logos and part numbers.

I installed them this Tuesday along with; new Valvoline AFT Dex/Merc and as with every previous ATF change I added 1oz/quart of LubeGard Red (both as per recommendations from DTT), adjusted the bands (Per Dodge Shop Manual = front band tq to 72 in. lbs. and back off 1 7/8 and then back band tq to 72 in. lbs. and back off 3 turns) new filter, gasket etc.

Test drove for 20 miles or so once everything was up to normal temp, I took it from a dead stop thru the gears on a few high speed runs and then just regular driving for another 10 or 15 miles to cool down. Didn't go anywhere yesterday and this morning I went out for coffee and a few errands - all was well. This afternoon, however, I went to visit a buddy and he and I took a short ride thru town, mostly 25 to 40 mph. Started out about 10 cars back a light, it didn't shift out of 1st, gave the go pedal a push let off quickly and it went into second, light turned red. Then the light turned green and the truck was stuck in 2nd, pulled over, turned it off, restarted, shifting normally. Dropped my buddy off and headed home. WTF!!!!


I'll call Tim tomorrow and see what he thinks then report back. In the meantime if anyone has any ideas let me know. I can't imagine there's any sensors left to replace and I haven't ever heard of a trans computer going bad or causing these shifting anomalies... More to come...

 

[cerberusiam]

The TCM is in the PCM and yes they go bad from time to time. You would have to log the actual gov pressure and requested gov pressure to see if there are differences, that would tell you if it is the components or something else.

You have a couple more things to replace before digging deeper or thinking PCM. The VB harness is frequent issue and should be the 2nd thing replaced for these types of anomalies along with a thorough inspection of the trans control harness to make sure there are no scuffed or pinched wires.

When you replaced the gov solenoid if you did not pull the gov housing and clean it out you left the potential source of problems in place. The OE housing has to many sharp corners and restrictions that will clog with fuzz and other FOD, could be a little piece of something floating in there and plugging the solenoid screen or orifice. The OE solenoids are junk, they used to be bad but not have gotten really bad. On a built transmission you toss that solenoid and the stock gov housing to replace with a DNC aftermarket housing and larger solenoid. That will get rid of most if not all the problem's with the solenoid. The transducer is an even bigger POS, the BD piece seems to be a much better option and will stand the abuse and problems that develop much better.

If that doesn't help then you are back to sticking valve sin the VB or a potential PCM problem. Have to have some live data to see where the issues really are.

 

[Joe Mc]

Hey Cerberusiam, thanks for reply. I spoke with Tim @ TRE (built trans back on 03) and he suggested the harness could be the culprit. So I replaced it along with the solenoids for OD that come with it. I purchased a gasket kit so I could replace the gasket on the Gov Sol / Transducer block and yes I cleaned everything inspecting for little tid bits and there were none. Unfortunately same situation repeated. When the odd shifting takes place it is very intermittent sometimes it'll go days and be fine others it happens 2-3 times in a day, so Tim and I feel it's electrical and not mechanical. He suggested checking out the voltage on the DTT transistor box that was installed when built, electrical connection at trans to internals and the harness outside the trans and go over all grounds. Last resort, as he has had a few experiences with new solenoids etc being bad out of the box, was replace solenoids and internal harness, but I'm going to check everything else again before spending another $200 in parts and the pain to drain, drop VB and all that again. More to come, hopefully it will be success...

 

[Joe Mc]

Cleaned grounds at DTT noise filter and transistor boxes, replaced ground end loops. Checked voltage at transistor box to harness key on engine off, Tim said should be 4.6, it was 4.5. Adjusted screw up to 4.7 and back down to 4.6, connected everything back up and went for a long drive. All is fine, for now, been driving about 3-4 days now without incident. Seems odd that 0.1 volt would solve anything, didn't think things would be so sensitive to act up due to 0.1 volt variance, but who knows? I'm being optimistic, unusual for me, but we'll see what time tells... will report back after a week or so, hopefully with "all is well". More to come.*

 

[Joe Mc]

Its been almost 3 weeks now and last week I took a road trip to Pittsburgh and back without incident. Looks like all is well again. Guess being 0.1 volts off was part of the problem. Calling it done. Thanks for replies and reading my plyght.

 

[Joe Mc]

Just an update, another trip to Pittsburgh and some miles in between, all is well, thank goodness.
McCazer out.