I currently have a 94 camaro with a 355 LT1, hot cam, .030 bored over, 1.6 rr rocker arms, working on headers and y-pipe, CAI, exhaust, and a 4l60e with a 3500 stall.

I just bought a rebuilt 4l60e and the car is going into limp mode, and its NOT the trans, it done it to the old one also. We have no idea whats causing it and its not throwing codes, we think its something in the wires going from the pcm to the trans or the PCM itself.

Our old 4l60e is still working, so we know its not the problem. We had it scanned at a shop, no codes, the guy said he cleared the pcm and the car had every gear and drove fine! but once the PCM picked it back up, it went into limp mode again.

The car has NO first in manual shift or auto, second in manual, third in either, and NO OD. It launches in 3rd at all times.

Any ideas on what this could be? One shop wanted to power the trans on it on (seperate battery on something) and said that would fix it. Would it? and if so, what do I need to do to do this?

thanks in advance!

 

I see that no one has taken a shot at answering it, probably because there is no obvious answer.
If the trans shop could force every gear using a scanner, then the wiring has to be OK.
I would first use a scanner to verify that the TPS, MAP and MAF are sending reasonable values; I would also try disconnecting the MAF to see if that restored shifting.
If the PCM was tuned before, I would next start with a stock tune to be sure of my starting point. If it was tuned, I wonder if the person disabled too many codes. I have not heard of a PCM going into limp mode without throwing a code.

I'm probably missing something, but after that I would try swapping out the PCM.