I have a 2001 Ram 2500 Diesel. When I am driving at aprox 50 mph, the trans seems to either be getting air or attempting to shift down. It is only for a split second then returns to normal. It is more apt to do this when cold. If I take the truck out of overdrive it changes nothing. I was told its a TPS but I would like some more input. Any sugestions?

Any error codes? http://mopar.mopar1973man.com/cummins/2ndgen24v/obd2-error-codes/obd2-error-codes.htm Might try re-grounding the APPS sensor... http://forum.mopar1973man.com/downloads.php?do=file&id=12

Mine just got done with that same thing, I just recalibrated the APPS and all is good again.

Cover my tail again... Yeah he's right you need to try that to before doing serious changes...

I replaced the brake light switch on my 2002 3500 automatic and that cured the problem of it kicking out of OD and unlocking the convertor or whatever it was doing. There is a problem with these switches and I think some glue on the new switch might even help so it doesn't "self-adjust" after it is installed too. These switches have a pin that slides into a tube so it can self-adjust when you install it but I think when you hit some big bumps that the pedal bounces and pushes the rod in further and then if there is and bumps it will let the contacts in the switch open the circuit. One thing that you can do is when you are driving and it acts up hold your brake pedal up with your foot and see if that cures your problem. If it does then likely you will need a new brake light switch. If you do replace the switch put on safety glasses and take apart the old switch so you understand how it works as a self-adjusting unit.