Lockup in OD, cant make up its mind.
 

Our 1 ton just started something wierd a few days ago wanted to see what you guys think.

If you ease away from a stop, it shifts fine, but when it comes time for the TC to lock in OD it locks then unlocks right away several times, lock-unlock-lock-unlock-lock....you see a pattern here. If you give it a little throttle, it locks up and stays that way.

If you pull the truck a little harder it works fine, it locks the TC right when it shifts and stays locked.

Im thinking maybe the speed sensor is going bad and the truck is going into OD a little to soon.

Another thing, we have a manual switch to lock the converter and if we use it the TC stays locked just fine, its only when we let the truck have control of the TC lock it has problems.

http://www.suncoastconverters.com/im...d%20rewire.pdf

24 Valve APPS
Rewire Ground Instructions
1994+

Lock-Up-O/D shuttle/hunt

Symptoms: At steady throttle usually at approx 40-50 MPH the tachometer will rise and fall approx 150-200 RPMS as the Torque Converter Clutch engages and dis-engages.

Problem: Electrical noise in the conducting wires running from the PCM (power train control module) to the TPS ( throttle position sensor).

This may be verified by observing a scanner while the complaint is occurring. The PCM will command loc-up on &off, the transmission is only doing what it is being told. This is not a "transmission " problem. Working on the transmission will not fix the problem. The PCM reacts to monitored voltage spikes caused by the TPS power and signal wires picking up electrical noise from other wires in the harness. The primary culprit is the AC voltage produced by the alternator. Replacing TPS’s,sensors, or PCM reflash almost never fixes the problem.

Solution: Make sure both batteries are in good condition. Make sure all battery cable connections are clean and tight. Make sure all ground connections are not corroded, this applies to PCM, TPS, and all ground connections on chassis and engine. After rewire it is sometimes required to "re-learn " the TPS (APPS on 98.5 +). Here’s how: disconnect both batteries for 15 minutes, reconnect batteries, turn ignition switch to run position (do not crank engine), slowly depress the accelerator pedal to the floor and release, turn key off. Now you may start engine and road test to verify complaint is fixed. There is a very rare occurrence of the PCM itself being defective, this is the exception not the rule. Try the most economical fix first!

If this doesn't work you will have to get a noise filter.

That sure sounds like our problem.

Seems wierd that it just started doing it, but we could have a corroded ground.

Another possible, we just put on a raptor fuel pump, that thing has some pretty good size wires going right to the batt, maybe some electric noise from those.

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Well, we did the re-ground of the apps and it seemed to do the trick, we will drive it some and see if its cured.

Its been several days now and the TC lockup is working as it should, so the extra ground did the trick.

Thanks for the info.

i have the same prob. will checking ground and connections really work?? and how? i am new to diesel and start my training this fall.. i have a 98 24v by the way

Yes,It is a common problem with these trucks.You check for tightness and make sure the ground connections are clean.The APPS sensor(TPS) is under the black cover in the engine compartment.Take the cover off and there will be a connection under there.Follow the direction in this link..

http://www.suncoastconverters.com/im...d%20rewire.pdf

I haven't had this issue ever, but I also put thins "upgrade" into my truck shortly after getting it. Anything simple and easy like this I will do right away, and suggest everyone does it as well. Preventative maintenance, kinda. :tu:

This curred my lock up problem as well as my cruise control. Setting the cruise control used to be like hitting a nitro button. Thanks
David

Glad it helped.:tu:

This is an old post and i cant get the rewire to come up. I am having the same problem