Driving a 1994 Silverado and the transmission (4L60E) will shift fine until 3rd, then it doesn't want to go in OD or will not downshift after that. Stays in third unless I shut the truck off. Then it'll be the same. Shift to third and stay.

When I disconnect the battery for a few minutes and retry it'll run like it should. Go into OD and downshift but only for a few miles then its back to being stuck in 3rd.

I have not had the opportunity to put in on a computer to see what codes come up. I'm gonna try that today.

Does anyone have any ideas what's going on with this? Any advice would be appreciated.

 

I had a problem once where it wouldn’t go into overdrive except at the beginning of a drive - a 93 5.7l with a 4l60e. In my case it was the membrane switch in the pan. It had a crack in one of the membranes and with pressure would leak in and the contact would fail. After it sat a bit it would evidentially drain out and work for a while.
The selector mech on my 4l60e moves a shift piston which directs pressure to different sections the membrane switch ( not sure what it’s actually called) and the switch tells ECM what position the gear selector is in. I think you should be able to see what gear the ECM believes it is in with a datalogger (at least TunerPro will) and see if that is correct.

If if not that, I don’t have idea or experience with all the ways a auto trans can go wrong! Hopefully someone else has ideas. Good luck!

 

It's called the pressure switch manifold. My trans still wouldn't shift correctly after I performed a full rebuild. I replaced the pressure switch manifold and the problem was resolved.