Hi all-

Been awhile for me on here. Hoping to find some help with my 2002 7.3 PSD 4x4 F-350 with DP Tuner chip with 105k on the clock. Recently it started staying stuck in 2nd gear until high RPM's, and then eventually it would shift to 3rd. After that short episode the O/D light started flashing, but eventually reset itself. Then truck performed flawlessy for a couple of days. Did a 180 mile drive to Seattle and it drove great. Returning from Seattle it did great in overdrive and all for the first 60 miles. Immediately after getting off of the freeway it wouldn't shift out of 2nd gear after a stop light. Trans temp was around 170 at this time, normal is 140-150 for me with the Tru-Cool cooler I have. Parked the truck, let it cool down and went to the water park. Returned 2 hours later and hit the freeway. Truck shifted all the way to 3rd no problem, but would not shift into O/D. If I backed off of the diesel on a downhill slope or flat, it sounded like it wanted to go into O/D, but as soon as i applied the diesel gently, it would shift to 3rd. Drove the last 120 home with O/D off and it didn't get any hotter than 170-175. Tried to run codes from a home reader and found none. Changed the tranny fluid and filter around 60k with full synthetic. No recent trauma or heavy hauls with it. Not sure what other information might be helpful, but let me know and I'll provide it. I think it's something TC related, but trying to decide on a diagnostics or if given the mileage it would be best to do a rebuild on the whole tranny if it is TC issues. I've also seen on here mechanical diode failures. Thanks again for the help!

 

I don't see how it could be converter related. The converter doesn't have much to do with the 3-4 shift. Mechanical diode failures will cause it to not upshift from first gear. And no 2002 had a mechanical diode.

You need the codes. Obviously the reader you have can't read transmission codes. Get the codes read somewhere that has the right too. Auto parts stores CANNOT read these codes.

 

Thanks for the info. To make it even more interesting, the tranny performed great on the way to work this morning. No shift problems at all and overdrive worked flawlessly. I'll wait and see if it does it again. Might be a possible loose connection somewhere that only surfaces when the connection is just off a bit? Thanks! Your help makes me feel like maybe it is more of a electrical issue and not a mechanical issue? Thanks!

 

That would be my guess, but it's only a guess. There isn't enough info here to point to anything specific.