Transmission or Torque Converter problem?

Question

98 Dodge truck 1500 4x4 Quad cab short bed, Gasoline 5.2L (318 ci.)
4-speed Auto w/overdrive with 60k mi.

Bought the truck new in 98 - 1st year was ok. Started pulling a tiny tent trailer in 99 and noticed on long hauls that the torque converter was locking & unlocking every time I hit a small or large bump. Took it to the Dodge dealer many times (more than 8 times) for this problem but they could not find anything wrong. The dealer said it may be a short in the electrical system somewhere but each time could not find it.

After the warranty has expired it still continued to do this a few times a week.

Since May of this year I changed jobs and now have a daily commute on the freeway at sustained speeds above 55 mph. Now the TC is unlocking/locking on every bump sometimes every couple of seconds. I have scanned this newsgroup for help many times and also

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and have tried to track it down. I got out the voltmeter and checked the throttle position switch and brake light switch. They were both ok.

Re-routed the spark plug wires so there was no induced current in other nearby plug wires.

Cleaned the battery and the frame ground wire.

Checked the manual 3-key on/off sequence to look for any error code. No error code.

Tried to follow the instructions on forcing the PCM to lock the TC by running a wire & switch off of PCM pin #54 but could not do it because the PCM wiring was not labeled.

This week, I manually switched off the overdrive before getting on the freeway and at 55+ mph the TC still locked and unlocked. This is with the OD switch off!

Summary: Now remember this locking/unlocking has only occurred when the truck goes over a bump or encounters a sudden change in wind direction.

Now for my question(s):

Is there a fuse or a way to disable the transmission solenoid for the overdrive lockup (like the manual OD on/off switch should have done) so I can test to see if its 4th gear or not instead of the OD (TC lockup)?

Does anybody have a sketch diagram of the PCM wiring plugs so I can locate Pin #54?

Does anybody have a sketch of the transmission showing the TC solenoid so I can pull the pan and check for a broken wire?

Anyone have this type of problem before?

End of questions If you don't know, don't guess!

Mr Ed Dodge owner since the mid 70's

Max Dodge · Accepted Answer

There was a tech paper written that involved location of the alternator wiring in proximity to the TCC wiring. Marsh Monster came up with it, and I may have buried somewhere. The fix was to wrap the alt wire in tin foil, which seemed odd until the deal was explained.

Lorne · Answer

I would check the brake switch.  If it is worn and starts to make contact it does tell the computer that you have touch the brake pedal and it will unlock the torque converter.  Lorne

SnoMan · Answer

I agree I think you will likely find this to be the cause that it isworn or out of adjustment. Good tip!!!-----------------

John Kunkel · Answer

Did you check the brake light switch under the same conditions (bumps in the road) in which the converter unlocks/locks?

The next time you're in the situation where it's unlocking/ locking, place the top of your foot under the brake pedal and apply a firm upward pressure and hold it that way for a while. If the converter stops cycling, the switch adjustment is the problem.

Mr Ed · Answer

Lets make this the end of this thread!Thanks for all the tips, Yes, I drove with my foot under the brakepedal so it would never engage the brake light. Tried to make sure thethrottle didn't move over bumps and did all the testing I could butcouldn't figure it out. My gut instinst was the solenoid in thetransmission instead of the TPS.Anyway I got feed up with it yesterday because I feel that there willbe some transmission cost in the future and traded it in for anothervehicle.At this point I needed to cut my losses. Also my job, making rocketsfor Israel and the US Army takes my total focus. So again, thanks butit's now somone's elses problem.Mr Ed(a Dodge owner till the day I die)

SnoMan · Answer

Kinda a bit extreme way of fixing it. We can now wait for new owner ofit to post about the problem. Glad you had a solution that you werehappy with though. -----------------

Transmission or Torque Converter problem?

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