sticky valve ?

[ronsws6]

I have about 25k on my rebuild so it's pretty fresh.* One day while in overdrive the car started switching in and out of OD to 3rd gear. Later, if it got caught in 3rd , I could blip the throttle and it would go back into OD. Now I have no OD at all.
Could this just be a sticky valve? Bad solenoid?

[JaycenK]

Are you sure it was shifting from 4th to 3rd?
In a 4l60e you have 3rd and 4th with lockup. Usually if you have the manual valve in the OD position then you will go 3rd non lockup to 4th and then lockup in 4th. It would be wrong for the trans to shift from lockup in 4th to 3rd with out a large input of throttle increase. When you say you blip the throttle and it would shift it sounds like the it was going into lockup in 4th. A bad A or B solenoid would not cause a problem with 4th because both are on in 1st and only the A is on in 4th. If one was bad you would have a problem with 1st where both are on, in second only B is on, in 3rd both are off, and 4th only A is on.
Here is a test.
Take off at normal to slow speed and manually shift the car. Start out with the shifter in position 1st gear. shift to second at lower rpms and when you get to third gear at low RPMs, keep the shifter in third and you should fell it shift to third and then you should feel the Torque converter lockup which will feel like another shift at around 35 to 50mph depending on throttle level. after it locks up go to 4th but before you shift increase your throttle about 25% from where you were in third. Now shift the shifter into OD and you should feel it shift into 4th. Now back off the throttle a bit and then you should feel the torque converter lock up again in 4th gear at 45 to 55mph again depending on how much gas your giving it. If you don't feel the torque converter lock up in 3rd or 4th, it is probably a bad TCC solenoid. If it locks up in 3rd and dose not shift to 4th at all then it is time for you to have the trans side of the PCM scanned. I would really say have it scanned before you change any parts just to make sure there isn't something else going on to cause this.

[ronsws6]

Thanks for the info . I am clueless when it comes to auto . I know that when its in the shifted OD at 55 if I shift down to 3 nothing changes .

[JaycenK]

Ok yea I would have it scanned then. You have to find someone that can scan the trans side of the PCM. a regular engine scanner wont do it. Not to sure thats an electrical issue because most everything that need to function electrically has already done a job by the time you get to 4th. May have something to do with the 4th apply piston if 2nd gear works fine. Not sure about that so don't take it to the bank if you know what I mean.

Who rebuilt the trans and did they do a stock rebuild or preformance?

[fieropope]

if its not electrical it would be the outer piston of the servo asembly,the seal or the pin wore the bore out ,which would allow second to function fine but not engage 4th .or even trickier is when a solenoid is physically bound so that the computer doesnt recognise that there is an issue .thus not throwing an MIL. autos can be tricky but once you understand the theory you get the concept quickly .