4l60e shifting problem

[streetsrfer1022]

My girlfriends 93 chevy step-side pickup recently stumbled upon a weird shifting issue that I cannot figure out.
It will shift just fine when the engine is cool and shifts normal no hard shifts or anything. But, once the truck comes up to temperature, it will downshift to first gear and will no longer shift. It still has reverse, neutral, and park but will not shift automatically. I have tried to manually shift it and still nothing.
I just changed the fluid and filter and still have the same issue. The fluid did not look too bad and did not smell burnt so I went ahead and finished.
I cannot seem to find a whole lot about this issue anywhere online so it seems to be fairly rare. When I had to pan off of the trans, I immediately noticed that someone had removed one of the shift solenoids "toward the front of the truck" but has worked just fine before so didn't think it was an issue. I also noticed that the wire tray was broken by one of the bolts. Again, I thought it wasn't a big deal because it just held the wires up off the pan.
Has anyone else encountered this issue and found out the solution to this issue? Also, would running some Lucas trans fix help with the problem?
:bang:

 

[yevgenievich]

It is odd, because limp gear that the transmission should go to would be 3rd, not 1st. Being OBD1, ALDL cable with a laptop can be used to see what the computer is seeing. It might have a cross leak when it warms up, or one of the sensors fails when it gets at full temperature. Worth checking the output of the TPS (Throttle position Sensor) when the issue comes up.

I had an issue in mine where only 3rd and 4th gears would work, and that was due to a bad seal that would force the fluid to apply all gears if it shifted to first or second.

 

[streetsrfer1022]

yes i thought it was strange as well. It is definitely 1st that it downshifts to when it acts up cause I'm able to go 35 mph or so but thats winding the gear out pretty far. I am planning on talking to the transmission shop on monday when they are open and see if they can diagnose it for us but I figured I would see if any one on here had an idea of what it may be.

 

[Alexandr-Rychok]

Where the heck was i when all this was going on... Lol
I cant view any pics yet??? If someone can help me out that would be great.
Pretty sure of what has to be done but i have the muddiest poker rally in Canada to attend this weekend and dont wanna make my shifting problem any worse than it is... Lol

I noticed it shifts much better when the idle is down around 1300 rpms nut cant get mine to idle that low.

Since day one this grinding and poping out of gear thing has been my biggest pet peeve with this sxs.., thanks for the info

P.S... this should have the title changed to include the 800 models

 

[89Suburban]

Where the heck was i when all this was going on... Lol
I cant view any pics yet??? If someone can help me out that would be great.
Pretty sure of what has to be done but i have the muddiest poker rally in Canada to attend this weekend and dont wanna make my shifting problem any worse than it is... Lol

I noticed it shifts much better when the idle is down around 1300 rpms nut cant get mine to idle that low.

Since day one this grinding and poping out of gear thing has been my biggest pet peeve with this sxs.., thanks for the info

P.S... this should have the title changed to include the 800 models