oldschooltruckdude

91 Chevy 1/2 ton 4x4 -

Starts off in 1st, winds up pretty high then shifts hard into 2nd, will not shift into 3rd or od, shifts into nuetral if you let off the gas. This goes on for approximately 10 minutes when cold, then all of a sudden its just fine and behaves normally. Whats wrong with this thing?
I'm not sure just exactly which trans is in this thing, would appreciate some help positively identifying it, please

Uncle_Charlie

If the transmission is a 4L60E and not a 4L60, you might get away with just swapping the throttle position sensor on the throttle body. It's something of a long shot, but it might work for you. If it's a 4L60, you are probably needing a rebuild. In my 97 Cheyenne, the TPS was the problem causing the harsh 1-2 shift. I'm not sure when chevy made the switch to the electronic controlled version of the tranny.

oldschooltruckdude

Now that the temp is no longer freezing, the trans has not acted up again. I havent had any more trouble fron it since shortly after the original post, so not sure whaty was going on.

bolts66

does your check engine light come on? mine does same thing when check engine light comes on, shut it off and it clears the code somehow, then shifts right again. ecm?

Masterfixalot

Chevy made the swap from the 700R4 non electric to the 4l60E in 1993.