Transmission problems
 

I have a 98 dodge, transmission is shifting in and out of OD, read other post but all seem to be about 97 or older. Checked error codes, p602 came up, used haines manual to troubleshoot. To calibrate the throttle positioning sensor, I turned the key on, pressed the throttle to floor and back off, is this the right procedures? Only notice the problem when truck is up to normal operating temps. Any input would be appreciated.

Do some more searches - many posts on this - caused by electrical noise spikes. Clean battery terminals, grounds, noise filter, etc.

Check the brake light switch. Next time pull up on the brake pedel with your foot to assure the brake light switch is off and that might keep it in OD. That worked for me until I replaced the brake switch.

one ground to check very closely is the alternator case ground, which runs off the alternator case and grounds on the front of the engine block right below the thermostat housing. one other thing to check is the trans temp sensor and to solve my same issue i simply wrapped the two field wires out of the alternator with some small wire and connected it to the alternator ground to bleed off any field winding volt spikes.

Chris

I read on one of the other diesel site, that it could be a frequency induced problem from the alt. the first step is to locate the black/tan stripe wire going from the back of the alt to the passenger side battery. Wrap about 4 to 6 inches of aluminum foil around wire where it starts behind the alt. Then wrap that in black electrical tape. Hope that fixes it before spending any money on your problem.

I would do a APPS reset first and load test your batterys. I ahd the same problem last fall, Apps reset helped some, took it in for a trans service, no real change. They also load tested my batts at that time and they were low (60% and 70%) about a week later I replaced the batterys and problem gone :) It would help folks ansewer your questions if you would go to the user CP and fill out your signature listing what has been done to your truck