I had a '94 k1500 4l60e tranny burn out its 3/4 clutch pack. After having it rebuilt, it doesn't have 1st or 4th. It starts in 2nd, shifts to 3rd and stays there. Park, rev, and neu are fine. If you manually shift the lever to 1st, it still stays in 2nd.

The mechanic is stumped. We have changed the soleniods and checked the wiring. We disconnected the computer harness and manually grounded the wires, and could hear (engine off of course) both solenoids actuating. We switched wires for the A & B sols at the computer, and still got 2nd and 3rd, although in a different weird pattern. We connected a diagnostic computer up to the ALDL while driving, and the truck computer said it was starting in 1st, shifting to 2nd, then 3rd, then 4th. Clearly it was not.

It sounds like an electrical issue, except the wiring is good, and the sols and computer are working fine. Is there anything mechanical that 1st and 4th have in common? The TC doesnt lock up in 3rd either, although that problem seems mute at this point.