I am working on a 4r70w in a 99 expedition xlt 4.6L 4x4. when upshifting from 2-3 and 3-4 car registers error code.none at upshift 1-2 at any rpm. error code at 2-3 upshift only at 3000+ rpm.error code at 3-4 upshift at 2000+.

no gears slip. tranny performs fine- at 66000 miles. fluid is red with brown but NO suspended particles. overdrive/ error code light (on gear selector stick) always resets fine (ignition off) and when flashing still has overdrive gear. No tranny driving performance issues Ive noticed (accept maybe downshifts a little bit firmer then before- but this may be my imagination!)

cant get code read until Monday. what would most likely be fault with the above syptoms :
1) 3rd gear solenoid / or other solenoid?
2) piston/spring in valve body/ power valve spring?
3) speed sensor?
4) fluid/filter change?

or if I missed it- whats the most COMMON thing it could be with these symptoms that I dont have listed???????

THANKS!!!

thanks, tryin to be prepared for what to expect. plan on changing fluid and any bad parts myself , since tranny seems easily accessable compared to other trannys I've worked on.

 

With the symptoms listed above a transmission company says Ill probably get a torque converter slip code?
so this could mean the pwm solenoid or the tcc solenoid or?
Thanks for any ideas.