Automatic transmission fail

Transmission only gives me 1st and 2nd gear. I stop research it. Start the truck back up, drive away and it has all the gears again…

1994 GMC 2500 4x4 454 Automatic 170000 miles

When was the last time you changed the transmission fluid and filter on your truck?

Fluid is good, Filter I have no idea

Man, wish I could help you. The only thing I know about auto transmissions is they cost a lot to have rebuilt and I don’t have great luck with them. All I would know to do is change the fluid and filter. Your trans in the 1994 model should be electronically controlled, or at least it was on the 1/2 ton GM’s in 94. If it happens again, you might get a good trans shop guy to ride with you with his computer plugged in. It’s possible it could be an electronic fault rather than a mechanical one.

Thanks brother, I going pre computer

Progress is not

Maybe the transmission fluid just needed to be a little warmer to get it working again. While you were parked after the first drive, it had a chance to distribute the heat throughout the transmission. Or if this is a seldom driven truck, maybe it took some time for the transmission fluid pressurized from the first drive to leak back down and fill all the nooks and crannies inside the valve body. Beyond that, you’d have to find a service manual for that transmission. They have one at the local Barnes and Noble bookstore for my Ford C4 transmission; you might try browsing there in the 'transportation" section, they may have one that applies to your transmissions too. Conventional automatic transmissions don’t differ that much from one to the other in how they work, other than the newer ones use electric solenoids rather than pressure operated valves in some cases to direct the fluid flow in the valve body. If you can find a service manual for a transmission similar to yours, that might contain the info you need.

If I had your problem on my C4 transmission and asking here didn’t turn up the answer I’d drop the pan, clean it out, replace the filter, and do a re-fill with fresh fluid as the first step. After that, check for transmission diagnostic codes .

That’s about what I was thinking, still not right. It Should work at -50. The truck did sit about 5 days so hard to say. I’ll put a filter in it and see what happens. Thanks

Suggest to also sieve the old fluid that comes out for an unusual amount of metal debris.