I have a 1994 f150 with a 4r70w Tranny. It works very well and pulls good but all of a sudden it all changed. Now the engine revs very high to shift from 1st to 2nd and again from 2nd to 3rd. I can do the shifts manually from the steering column. When on the highway its runs fine but as the speed drops then the tranny slips back into the next lower gear and then I have to rev the engine high once again for it to shift into the higher gear. I have replaced the three solenoids in the base but this did nothing to resolve the issue. I then removed the entire wiring harness and checked the continuity across all the pins and checked for cracked or broken wires. Everything seemed to be fine and this as well did not resolve my tranny issue.
Can anyone please tell me if there's anything else I can do before I tear it down and do a complete rebuild. ?????

 

Sounds like the clutches are going out. But I'm no tranny guru.

 

Thanks worm. I was kinda thinking it may be electrical and really hoping it was but the more I dig into this, it seems the more i'm leaning toward a total rebuild. There's no shame though. There's 299800 on the truck now and I just can't bear to let it go. It was my very first truck and I love it. Any help, assistance or advise would be greatly appreciated.
Thanks folks.

 

Reading the codes is always the first step when diagnosing an electronically controlled automatic transmission. The places that read codes free CANNOT read Ford transmission codes. It takes a good independent shop or a Ford dealer.

 

I had a code that was flashing 122. it's low voltage on the throttle position sensor. I changed the sensor and the problem with the transmission went away. I was told that when the TPS wasn't working like it should have, the PCM puts the transmission and engine in a hard fault mode as it did. I also had a 998 code, that's the fault code. All is fine now and I've learned lots from all this. Thanks everyone for the assistance in the trouble shooting.