Okay, I am far from a Dodge diesel expert and am not embarassed to admit my ignorance. The problem my truck is having, and appears to be getting worse, is the repetitve shifting of the transmission between 3rd and 4th at 45 - 50 mph. I just did a transmission "tune-up" including new filter and fluid, adjusted front and rear bands, but had no effect on the shifting problem. The only mod which I use is a Superchips tuner having set the tuning to "Perfect Tow". The truck has 148,000 miles on it. Any help or suggestions would be GREATLY appreciated.

 

Been there, done that.

It is electrical in nature. Specifically, your ground wires from the battery to the fender, alternator to the fender, behind the ECM module on the passenger side firewall.

But first try cutting out the gray quick connector between the alternator & the battery / neg ground on the passenger side. It gets corroded and causes interference to the ECM.

The bad news is it will take a few hours to fix, the good news is it won't cost nothing.

Do a search for more info.

 

Thank you for the reply. This thing has been driving me INSANE. I will work on this tonight. Thank you again.

 

does it do it under 2000rpm?
mine does the same sometimes but not once i hit 2k goin down the road just curious

 

let us know if that fixes it.

 

Clean the battery terminals first, if this helps you are on the right track. It can caused by weak batteries also.

 

SUBJECT: '99 3500 auto tranny repetitive shifting

Thanks to all who offered help. It is greatly appreciated. I cleaned the battery posts (very little corrosion) and the 2 disconnects, and, knock on my wooden head, it appears to have solved the problem. I have dealt with many wierd problems over the years caused by corroded battery terminals but never a transmisson problem. Thanks again!!!

 

The shifting problem is caused by electrical "noise" due to the bad grounds.

Glad to help.

 

If It Happens Again ,it Could Be Your Throdle Positioning Sensor.good Luck.