Took it to a mechanic and he found the ESS connection had a short, so he soldered the connections, got it to charge but still no trans shift out of second.

 

Ok, you are part way home, now it is time to diagnose the trans. mechanically the trans does not use electricity to shift, the only electric function on the RE that would affect gears 1-3 is the Governor pressure. Either get a pressure gauge on the ports and read the line pressures, or probably first, look for any codes related to the governor pressure circuit.

 

The governed pressure solenoid and sensor were replaced, and now the ASD comes up on the code scanner

 

I had the GEN light twice. First time brushes were worn. I replaced them on the tailgate in the middle of the Nevada desert. The second time my rectifier burned up. I could smell it when I stood in front of the truck. I replaced it myself. It wasn't hard to do.

 

Ok, if the ASD is not being brought in with the ignition switch, the PCM doesn't think that your truck is running, not only won't you have charging, you won't have any OD, AC, etc......... And obviously the Governor will not be operating because the truck thinks it is shut off.

What year truck are we taking about, 96,7 or 8?

 

It is a 1996