Engine/Transmission (1994 - 1998) problem with overdrive cutting on and torque converter locking in and out on 95

[TFaucette]

have a 95 47rh that does not slip or shudder but takes forever before the overdrive decides to turn on and then the torque converter constantly locks and unlocks, plugged a scan tool up and drove it and when computer told to cut on the overdrive would turn on and you could watch and lockup solenoid was constantly being told to turn on and off. throttle position seemed to be reading properly, what could cause the computer to act up telling it to lock and unlock constantly and be so hard for it to tell overdrive to turn on? one guy suggested pressure sensor on trans cooler line could be faulty

 

[JJPage]

TF
I have little experience with the 1st gens and their electronics. Having said that, it seems I have read quite a few threads, where similar trans behavior was attributed to failing batteries and or loose/corroded (chassis)grounds. You may want to start addressing those items first. I am confident cerb will see this thread and help set you in the correct direction/steps, before you start randomly replacing solenoid packs and such.
Jess

 

[TFaucette]

it's a second gen 1995, but i'll see about ground connections could a bad pcm act like that?

 

[cerberusiam]

The lock\unlock of the TCC is usually noise or signal variation on the control circuit and that has so many sources it is a problem. Basically, start verifying the batteries are good, all cable connections are good and clean, all grounds clean and tight, and have the alternator checked to make sure it is not letting and AC current thru to the control systems. The TPS is also a likely candidate to check and see if it is providing the correct readings to the trans controller. If everything else checks out then it is time to look at either the solenoids, the PCM, or VSS.

 

[Cosmo]

Have you checked your fluid level?

 

[jtwcummins]

Had a 97 auto from 1/97 - 11/07. Big problem with TPS on early 12v trucks. Use a good DVM or better yet a scope and monitor the output from the TPS. Move the throttle slowly thru its travel with engine running and glitches should show up if the TPS is bad. Big issue was TPS set to low, not really adjustable but with a little imagination you can get a . 1v or more change by loosening twisting and retighten. Twist doesn't mean with a wrench! Should be close to 5 volts at idle. Issue also with noise on signal lines. People have rerun the wire from the TPS to the ECM to get away from other lines. DTT use to sell a filter, I did this and no more problem, to clean it up.

Since the engine compartment is not an electrical component happy place, checking grnds is good to do. Especially the grounds going to the fenders by the batts. Removing, cleaning with contact cleaner, using dialectric grease then reinstalling the under hood connections fixes most gremlins on older vehicles. A big percentage of swapped 'computers' check out OK.

 

[Dieseldemon]

Could also be the trans fluid temp sender in the output line to the heat exchanger

 

[DavidGardner]

Had the same issues with my 95 47RH. Contacted DTT and got the noise filter with instructions on how to adjust the TPS. End of problems. Now have 280,000 miles with no issues.

 

[TFaucette]

they were out today for veterans but online I only see noise filter for 96-up trucks is this the same one used in the 47rh?

 

[TFaucette]

also saw tps adjustment/voltage can be an issue but saw the throttle position changing on scan tool but didn't do anymore than that. is it possible that could be an issue or maybe even the pcm it's self. checked all the grounds under the hood

 

[fox]

Brake pedal bouncing will also do it. How about cruise control? Does it do it also?

 

[DavidGardner]

The issue of the torque converter not locking up on first drive of the day is normal. There is a temp sensor in the transmission that will not let the converter lock up until a certain temp is reached in the trans fluid. Mine does that if the truck has sat over night or a long time in cold weather. It is addressed in the owners manual and normal. I would check with DTT again. I am sure they can tell you how to cure the issue.

 

[Ra Gor]

Had the same issues with my 95 47RH. Contacted DTT and got the noise filter with instructions on how to adjust the TPS. End of problems. Now have 280,000 miles with no issues.

what is DDT?

 

[cerberusiam]

what is DDT?

DDT is an insecticide used extensively in the mid 20th century.

DTT, on the other hand, is Diesel Transmission Technologies. The name is self descriptive.

 

[TFaucette]

picked a noise isolator up from BD for about a third the price and looks like the exact same product, haven't put it on yet but upon further research I seen that it was suggested that the "noise" came strictly from the alternator and to pull fuse for alternator to see if it quit acting up. but I was able to talk to previous owner (truck was bought from insurance salvage) and he told me that when he had it, he didn't have any problem with it. truck was not mangled, the only thing I did was pull out rear passenger corner, replace bumper and hitch. is it possible a jar from the wreck could cause this noise? or am I missing a ground somewhere at bumper or hitch?

 

[TFaucette]

ok its called a APPS noise isolator pn:1300030

 

[TFaucette]

finally got around to putting it in only takes 5 min and works perfectly