Slipping out of overdrive?
 

Hey guys well sometime last week, my truck began or has seem to begun to slip out of overdrive between 50-55mpg and only does it between those two ranges, I dont know if its the overdrive disengaging and rengaging the engine only jumps maybe 200 rpms when it does this? but I just wanna see if this has happened to anyone else and see if there are any good places to begin making sure its not a connection issue. But the tranny does have 237K on it without rebuild but I want to make it at least another 50K before I want to rebuild it so I can rebuild it right... but any suggestions and advice will be appreciated and other than slippin out of over drive its shifts fine....

It happens to lots of people, and is the T/C locking and unlocking. Try a lock up switch to see if the problem goes away.

http://www.tstproducts.com/Torque%20...p%20Switch.pdf

Next question what should I do if that doesnt fix it??? Id hate to have a switch I can forget to disengage lol

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Also Im gonna relearn my APPS and see if it helps any I think Ive been needing to do that for awhile now, but im not sure because my truck jumps into overdrive at 40 if im not asking a whole lot from it, if I have a load or stay above 2000 RPM it wont go to overdrive untill 55 mph, I dont know if this is normal as I have not driven another cummins with an auto..

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Also its says not to cut the wire so how would you go about puting in a ground wire? just shave off the insulation?

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UPDATE: I relearned the APPS and I accelerated kinda slow up to 45 and she didnt try to sleep and then I sat between 50 and 55 and she didnt slip so I hope this fixed it but, im not gonna get my hopes to high until I drive it a whole day without it doing it.... but thanks for the help and site! if this dont work ill try the switch..

If it doesn't fix it, it would most likely be the t/c solenoid, or a loose connection.

Adjustment to the throttle cable going to the transmission can change how long the trans stay in a gear. I have adjusted mine so it says in gear longer. Otherwise it would shift into 3rd at 18mph. The trade off is firmer shifts though.

Yes, just shave off some insulation, solder your wire on, and seal it as best you can.

Glad the relearn has helped, hope it fixes it.

yea it my truck shifts at 1st 20, 2nd 35, 3rd 45, and then it will go into fourth if im slow and will stay a gear lower if im, haulin butt.. but thanks for the info!

mine started jumping in and out of lockup horribly 1 week after rebuild. Between 50-60mph it was constantly searching for where it wanted to be.....thought something went wrong with rebuild.....lots of thread searching later found 3 free possible solutions......check/clean all grounds,make sure alt ground wire wasnt too close to the back of the alt,and .....yes,....wrap alum foil around alt ground lead.......went out to my driveway,alum foil and zip ties in hand (hanging head in embaresment that i actually had the alum foil walking toward my truck).....found 1 questionable ground...fixed.....alt ground wire was very close to the back of alt....zip tied back.....and,yes I actually wrapped about 8" of the ground lead in alum foil and covered in elec tape......almost 2 months later now and havent had 1 problem since,,,,,not sure which 1 of the 3 actually fixed the problem but I dont really care as long as it is gone!,,,,,,,just my .02

Yea thats what I have found too so if It continues I will try those fixes and if those fixes dont work the TQ lock up switch. What pisses me off it started happening when we finally get some real rain and its started this, but its not constant unless im in the 50-55 mph range but i dont think its a true tranny slip because I had slip in my old dakota and that thing would run up the rpms, so I think its something stupid (At least I do) im with you Id be ashamed to have the ford neighbors see me out there with aluminium foil! lol... but ill see if it does it again and if it does im going electrical huntin this weekend!

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UPDATE: Well my truck quite having the issue thank god :choochoo: so all is good but will keep all the advice just in case it happens again or so I can pass it on... but I also think having dirt covered terminals wasnt helping my cause either.. But the apps made a differece in how it drives...:tu:

one more thing to check is that your brakes are not comming on, if your brake pedal is even tapped it will unlock the torque converter.

yea I know thats not my issue I have driven 150 miles and no problem....

My truck was doing it really bad. I got a BD Diesel apps noise isolator for $26 off ebay and it stopped. Best $26 I ever spent.