01 expedition 1-2 shift failure

[bcmaxx]

Just hopped in the truck today, out of the blue it wont shift from 1-2, I hammer on it it over revs and hits 3rd. it will not perform 1-2 shift. going uphill 3-2 downshift is normal. Is there a solenoid that fails I can replace? the od light flashed until I cycled the key, i wish I wrote down the code, it was like po1752? my best guess. If it happens again I'll get it for sure. Any common failures I can look into? for now I added some seafoam to the tranny in hopes it will free up a sticky valve. Fluid and filter have been replaced, fluid condition and smell is excellant
2001 expedition 5.4 auto eb. Thanks

 

[bcmaxx]

I'll add, there is no slippage or anything funny going on,all other shifts are perfect. First thing I tried was a reflash

 

[FordandPolaris]

Sometimes things get weird when it is super cold like it has been. If it's the first time it happened, chalk it up to a fluke. Once my truck randomly would not shift to drive. Reverse worked fine. Trans shop pulled the pan and put it back together and it's worked fine ever since...

 

[bcmaxx]

1-2 shift failure. Still wont shift. I added seafoam. No go. If i manually upshift it is fine

 

[bcmaxx]

well good news, unfortunately I replaced the shift solenoid pack first and it didnt fix it, so I have a spare.... I got a transgo shift kit and a upgraded sonnax line pressure modulator valve. Took it all apart, and found the 1-2 shift spring in three peices on the main body. replaced all the springs, installed the upgraded parts and bingo. just like new but better!! Was quite please by how clean everything was, how little material was on the magnet. soooo happy dance

btw......I was told by a ford tech, another ford 4r100 owner, and a transmission shop iy needed a full rebuild, everything from worn clutches to broken one way sprag.. so I saved myself about $2300 and all it cost was about 120 in parts)

 

[nonwoven29]

Cool. It's always great to save $ and learn at the same time.

Thanks for the info!

 

[bcmaxx]

pulling apart tonight, about 1 in every 50 shifts it hangs in 2nd, i talked to my buddy at atlas transmission and he said the valves should move in the bores with no resistance, i know for a fact when i installed them and the new springs there was resistance. plan is to pull the front body dissassemble, clean the bores with special nylon brushes, clean, clean,clean and reassemble with some upgraded cooling goods

 

[JUST4FUN]

If the bores have any wear then you will have too drill and sleeve the bore

 

[bcmaxx]

dissassembled and cleaned, i managed to pinch the little spring on the line pressure modulator last time, it was shaped like a piece of macaroni haha. anyways all fixed and upgraded cooling parts on. no visable wear or burs anywhere. one tip is to clean the topside of the tranny where the pan bolts go through, it holds a lot of road gravel and dirt up there, I had to chase a few pan bolt holes because of it.