Recently purchased a 93 4x4 with a automatic trans. Truck runs real strong. Trans shifts firm, the guy says it recently was rebuilt(not sure to what extent.) Drove the truck probably 600 or 800 miles no issues. The rear main was leaking when I bought it and decided to go ahead and repair it. Local trans shop did the repair no problem. When I drove it home, it didnt seem to shift as firm as it had but I didnt give it much thought. 200 miles later going down the freeway and it downshifts ***. Back to the shop, slight tv cable adjustment and Im on my way. Seemed to shift firmer again so I thought it was good,ten miles down the road it downshifts again at 55, Im almost home, park it for a couple of days, check the fluid ,take off down the street and it wont shift in to 3rd gear. Could this be a coincidence or just bad luck . Why the downshift at 55 and now wont shift up. Im towing it to the shop tomorrow, Im hoping there hasnt been any engine damage from the downshifts. Is it possible that the problem was created by the R&R job or just happened to go to #$@ anyway. This seems like a reputable shop and Im hoping a rear seal doesnt end up alot more than I bargained for.New to the forum and any advice would be appreciated.

 

I don't trust tranny shops a lot of them are rip offs selling you a rebuild job when it only needed a adjustment . look it over real well and see if any of the adjustments have been messed with ,also get a second or third opinion.

 

The trans fluid should be checked as the manual advises--when the trans is at operating temps (hot). Set the parking brake, run the shifter through PRND21 and back up, then put it in neutral and check it. A little bit over full is not a problem.

 

My friend had the same issue, truck shifting soft and strange- 2 trans shops quoted him <$3,000 to fix- i told him to bring it past my house and I yanked the pan, cleaned it- adjusted the bands (super easy) and refilled the tranny, all issues fixed! Cost $14 for filter and gasket- $8 for cheap wall mart ATF. Done! I loved the truck so much i ended up buying it from him. Video of pan:
http://www.youtube.com/watch?v=98h1XkgKBWM

PS, my truck also downshifts when it should not- If I stomp on it at say 40 the stupid thing goes into 2nd at 2700RPM then upshifts to 3rd- its a issue that was corrected in 1996 with the 47re electronicly controled shift points rather than a rod connected to the throttle.

 

Trans shop says it might be my pcm. Probably a dumb question but is it possible to buy a re-built or do I have to re-build this one,looked around a little bit but cant find much info.

 

You can buy them rebuilt, but I'd put my money on the simple things first. Check the Throttle Position Sensors, if its downshifting from OD to 3rd thats more than likely the problem.

 

Havent heard back from the shop today but I forgot to mention that as well as the shifting problem the wif light was coming on and the speedo not working then jumping around. Morning I had it towed in the battery was almost dead and alternator wasnt charging. Illhave to call the shop tomorrow morning and mention the throttle position sensor to him.

 

Well its been three weeks since I dropped the old girl off at the shop. Shop owner swears by his diagnosis that its the pcm/ecu. Sent mine off and its supposed to be back by the 7th of July. Im hoping hes right and it solves the problem. Im a little skepticle first of all because everything seemedfine before he dropped the trans to do the main seal and second because this doesnt seem to be a common problem on these trucks.The availability for a rebuilt seemed to be pretty limited as well. I have no idea where he sent it to be rebuilt. Im no mechanic so any opinions or advice appreciated. At this point Im pretty much commited so im just hoping for the best, starting to loose a little faith but maybe Im just being paranoid.