i have a 98 dodge 2500 automatic with 79,000miles my problem is that when i first bought it it would shift back in forth between 4th and overdrive between 40 and 55 mph there are no codes so right as i was going to send it in my girlfriend set her car up for sale and had to drive it back and forth to work she drove it for about 2 weeks and when i got it back it stopped doing it. well it worked fine for about 2 months and now it started doing it again i can barely drive at those speeds because it starts shifting so bad. the tranny fluid is full and it doesn't smell burned any suggestions i appreciate

 

ok this sounds crazy but whats happening is electrical current from alternator is confusing the apps. what i did was unhook both batterys for about 1 hour turn key on to drain any left over current in system than turn off and wait the hour hook up both batterys and than turn ignition on and SLOWLY depress gas pedal all the way to floor and release SLOWLY back up than turn off truck and than start up and give it a shot also what i did was the wire from the back of alternator i think brown and white its the bigger wire i wrapped that in aluminum foil than covered it up with tape or something they sell some resistors on this site for this problem but ive done this about 5 months ago and all seems fine. good luck.

 

but why would the alternator only effect the system at those certain speeds what makes the overdrive different i did that and took it on a test drive and it seems fixed but we will see after a couple days driving thank you

 

I had this same problem. I actually used a battery wire and made it a ground wire from the tranny to the frame. Don't ask how this worked. A transmission guy told me to try it. Good luck

 

it could be emi like they are saying, or could be a bad tps/apps. you can try adjusting it. there are some articles on installing a resistor to get rid of excess electrical noise from the alternator. some will have you add a ground to the tps sensor ground wire. the last two trucks I worked on were a very severe case of the problems youre having, ended having o/d clutches wiped out however, the problem only occured around 45-50 mph and wouldnt do it all the time.

 

For anyone else with this issue i changed my tps and still had trouble someone told me to clean ALL the grounds and i found my problem. It was the ground for the TCM behind the a/c accumulator. This fixed my problem it has been over two years trouble free.