Newbie here with a 2000 diesel 2500 automatic. The problem I'm having is between 40 and 50 mph, the rpm fluctuates up and down like it's shifting in and out of overdrive. This only happens when I'm using overdrive. When I'm out of overdrive at this speed, the rpm's are stable. Also when I have cruise control on and in overdrive, the rpms are stable. What is my problem? I have already put in a new "throttle position sensor" but nothing changed exept my wallet got a lot lighter. Also I had the transmission checked by Coleman-Taylor and they said it was fine. Can anyone please help me? Thank you.

 

Moved to 24 valve engine and drivetrain for expert advice.

 

Several things have been known to cause that. Bad apps , bad brake switch, several different things. Sure sounds like an apps to me. Most likely. The brake switch , you would be having problems like cruise kicking in and out as well. Could be the throttle valve cable adjustment too. Do a search for throttle valve cable or TV cable adjustment. If you can't find anything I'll post it again. That is the cheapest/easiest thing to check first.

 

No it is a poor ground for the computer. Search for ECM ground or noisy ground. Many, Many guys have this problem. Clean your battery grounds well, shield the computer ground. There is far more detail in other postings. But trust me, it is that simple! Though time consuming....

 

It is not that simple. megamac is correct though to clean all terminals and make sure all the ground are good and clean. If this still doesent work find the black with orange tracer wire i believer running though the alternater bracket and over the alternater. Go to radio shack and buy a rf noise filter and install it over that wire. If that still doesent seem to work pm me and i can give you more ways to solve this problem. Oh the problem usaully is that the alternater is giving off rf noise and that wire is transferring it to the computer and messing with the signals it is trying to give to the transmission.

 

I had the same problem, I ran extra ground wires. I did the special apps wire splicing and wrapped the wire going to the alternator with foil. I reset the apps each time I tried something new. I ended up having to get my alternator rebuilt to fix the problem.

If all else fails take your altenator and have it rebuilt. FYI mine had 147,000 on the original.

Good luck.


Tom

 

It doesn't always have to be the ground. There are easier things it could be. It very well could be the ground problem as well, but don't write off the easy stuff first.

It can be that simple and is many times. Don't be so quick to critisize. We are all here to help.

 

i am not at all critizing i just helping the guy out. If we dont tell him what the actual problem is he wont understand what we are telling to do. And i had said in the second sentence that magamac is correct, i dont think that is critizing him.

 

It will be interesting to hear what he finally found the problem to be or what he did to amke it go away......