jknowles4

I have had this truck for almost a year and have asked a few questions about lock up and have done a lot of searching and just want to know where to start. Today while driving my converter locked up for the first time. I thought something was wrong with the truck. I let off the pedal and then slowly pressed down and it picked up rpm and then dropped rpm and felt like it gained another gear. I did this a few times and then it stopped.

Came home took off tps, cleaned it. Cleaned all the battery terminals connections and I can't get it to lock up again. Any help/advice is appreciated.

I saw the potentiometer thread and wondered where you can get one.

Big Deezul

you need to talk to a transmission builder. For some reason your VB is not allowing the converter to lock up.

Can you lock it manually with a switch?

jknowles4

I tried the switch but the year truck I have needs the computer reflashed for the switch to work. Found that out after I hooked it up!!!

oldblues

hi
cleaning the tps may not cure the prob if it is bad .

remove it and test it with a ohm meter to see if it works smoothly and is making contact inside .

also check for codes , some cause a fault !

jknowles4

Tested the TPS and that was the problem. Thanks guys!!!

jknowles4

Ok after I tested the tps the tranny locked up. Hooked to a trailer to go work today and it wouldn't lock up. Got home tested the tps again and it was right where it is suppossed to be. What do I check now????

dozer12216

RPM sensor on OD unit may be giving poor signal. did you check brake switch, and does speed control work?

jknowles4

Checked brake switch last night. Seems to be ok. It is making contact with the brake pedal. Cruise/speed control works. Truck shifts like it is suppossed to. This is driving me nuts. I finally felt what lock up is like and now I can't get it to lock up again. The trailers I pull only weigh about 4500 pounds loaded and you can definitely tell they are back there.

John Faughn

I've the best way to fix anything is , testing , get a wiring diagram , go to the connector on the trans and connect a multi meter to the wire that locks the TQ , it is done by grounding the TQ connection .
Then you know weather it the converter , or to look further , to the many aspects that control the converter lockup .
I do not know either way , but have not heard that a 96 needs to have a flash to add a lock up switch , but I like to have every thing work before adding mods , its a pain to forget to turn the sw off / unlock , when coming to a stop , very hard on many things converter ect.

jknowles4

Would my brake light and ABS light being on have anything to do with this???

John Faughn

The brake sw does more than just turn on the brake like , it turns off the TQ & cruse also .
I have had problems with mine since I bought the truck , put in a new sw , had problems with it a few mths later , could not keep it adjusted , sometimes those 2 lites would come on , so no lockup .
Some times the sw would keep the TQ from working ever if the brake lite was not lit , so I put in the TQ sw , will try to find out how to make it work later , but now I have lockup for the hwy .

MikeR

I hate to say, but putting up with that for a year seems crazy. Why not spend the 80-90 bucks at a trany shop and have it diagnosed?

I've never heard of a reflash just to get a mystery switch to work either.

jknowles4

I didn't really know if it was locking up or not for the past year. I posted a long time ago and I guess I just didn't worry about it. It's driving me crazy now knowing how different the truck runs while locked and it will be fixed.

As far as the reflash read here: https://www.dieseltruckresource.com/...mystery+switch

My truck falls into the 6 month production period that a reflash is needed.

caburnside

i think I am having the same problem here's a duplicate of what I posted in another forum, but it sounds like the same problem and I can't figure it out:

First off here’s the truck

1996 Dodge 3500 automatic trans 2 wheel drive with 229,787 miles
last trans rebuild 155,000
370 injectors, #10 fuel plate all the way forward, AEM workhorse, ATS exhaust manifold, Silverline 4’’ exhaust, blocked wastegate, star wheel turned, EGT, Boost, Trans temps.

I can’t figure this one out. The truck was driving fine yesterday until I exited the highway. Then when I rolled up to a redlight I lost all RPM’s. I cranked it back up and limped it towards a gas station. Here is what I do know: She has no power in low gears. Runs normal in top gear for the most part. The truck Idles in park and neutral fine but dies in drive or reverse. The truck when taking off from a stop sign feels almost like I am in a 5 spd and taking off from 3rd gear or something (it is going through shift sequence as normal, it justg feels that way)

I thought the problem to be the lift pump but when I switchd it out I still had the same problem. Now I am thinking timing possibly.

The trans guy says torque converter lock up but has not been able to look at it yet, and I do not think that is the problem because the truck is not throwig any trans codes.

It does throw two codes mentioning the speed sensor, and something about the ECM.

Any ideas?

jknowles4

Sounds like you need to check the tps voltage and make sure the throttle linkage is measured to spec.