Tranny Not Shifting After Swap

cml0101 · September 5, 2011

Earlier this year I had a 94 gmc truck and crashed and totaled it about 10000 miles after the rebuild on the tranny. It shifted fine after the rebuild and after the crash I drove it home and to a mechanic and still was fine. Well after the insurance company paid me I went and bought a 92 with no motor or tranny and had the mechanic swap the engine, tranny, computer and harness into it. Now it doesn't shift anymore. when i put it in 1 or 2 it seems like the same gear and drive and overdrive are the same gear. I've been driving it and having to put it in 2nd then when I get some speed I shift it to drive. I feels like the only gears I have in the truck is 2nd and 3rd because when I take off it goes a little slowand when I get to 70 it seems the rpms are pretty high. Does anybody know what's going on I really want to get this truck going again right I just paid a lot for the rebuild and it shifted fine then. I tried to talk to the mechanic but he keeps bsing me and he was a home mechanic that a friend told me about

possin08 · September 7, 2011

Earlier this year I had a 94 gmc truck and crashed and totaled it about 10000 miles after the rebuild on the tranny. It shifted fine after the rebuild and after the crash I drove it home and to a mechanic and still was fine. Well after the insurance company paid me I went and bought a 92 with no motor or tranny and had the mechanic swap the engine, tranny, computer and harness into it. Now it doesn't shift anymore. when i put it in 1 or 2 it seems like the same gear and drive and overdrive are the same gear. I've been driving it and having to put it in 2nd then when I get some speed I shift it to drive. I feels like the only gears I have in the truck is 2nd and 3rd because when I take off it goes a little slowand when I get to 70 it seems the rpms are pretty high. Does anybody know what's going on I really want to get this truck going again right I just paid a lot for the rebuild and it shifted fine then. I tried to talk to the mechanic but he keeps bsing me and he was a home mechanic that a friend told me about

Fluid level okay? Sounds like it could possibly be a problem with the torque converter, possibly he didn't fill it with fluid and its burning up. May explain the high rpm at 70 mph. What kind of B's is this guy giving you?

Doug_Scott · September 7, 2011

Earlier this year I had a 94 gmc truck and crashed and totaled it about 10000 miles after the rebuild on the tranny. It shifted fine after the rebuild and after the crash I drove it home and to a mechanic and still was fine. Well after the insurance company paid me I went and bought a 92 with no motor or tranny and had the mechanic swap the engine, tranny, computer and harness into it. Now it doesn't shift anymore. when i put it in 1 or 2 it seems like the same gear and drive and overdrive are the same gear. I've been driving it and having to put it in 2nd then when I get some speed I shift it to drive. I feels like the only gears I have in the truck is 2nd and 3rd because when I take off it goes a little slowand when I get to 70 it seems the rpms are pretty high. Does anybody know what's going on I really want to get this truck going again right I just paid a lot for the rebuild and it shifted fine then. I tried to talk to the mechanic but he keeps bsing me and he was a home mechanic that a friend told me about

Fluid level okay? Sounds like it could possibly be a problem with the torque converter, possibly he didn't fill it with fluid and its burning up. May explain the high rpm at 70 mph. What kind of B's is this guy giving you?

Not going to be the torque converter. First off, it is filled by the pump in the trans, not the mechanic when he installs it. Is there a tach on the truck? If so, what are the rpms showing at 70 mph? I am not understanding the reference to the wiring harness. Unless there is something already in the truck for the harness to connect to? Is the 94 trans the same as the 92? What changed between the years?

wavery · September 7, 2011

These swaps are seldom simple to pull off. The ECM has to recognize so many signals from the vehicle. It could actually be something as remote as the ECM not recognizing a signal from the dash cluster or vehicle speed sensor......... I'm not saying, that's what it may be, I'm just saying that there may be no simple answer to this one.

millhouse49 · September 9, 2011

sounds like the 2-4 band could have came off the mounting point when it was in the crash. the trans would have to come apart to repair.

GMstrong · September 11, 2011

Your best bet is too pull the pan these trannys are not hard to work on at all.i bet either the govnor or the pump itself might be going could very well be the thorttle valve inside the trans.Also did you blow out the cooler lines? this could do it to.