GMC Repair: 1998 GMC Sierra Starting Problem, sierra 4x4, gmc sierra

Question
I have a 98 GMC Sierra 4X4 with a 5.7 liter Vortec and a 4L80E Transmission. After replacing my transmission I was unable to start my truck without bypassing the solenoid. After some investigation I found a broken wire going into the 7 way plug in on the side of the transmission and another one on the 4 way plug in. After repairing them the truck once again started by key. A few months later I disconnected the battery on the truck to do some welding and after reconnecting the battery I was unable to start the truck again without bypassing the solenoid. (FYI...I ended up not welding anything so I know I didn't do anything to the pcm by welding on the truck. ) I've checked ALL the fuses, I've tried disconnecting and reconnecting the battery, I've left the key in the on position for 8 hrs with a trickle charger hooked up to the battery and I still can't get the truck to start without bypassing the solenoid. When I repaired the broken wires I used water proof connectors and I checked those to see if there was any corrosion. I'm at a loss and tired of bypassing the solenoid, but with 8 kids I don't have the money to put the truck in the shop and let GM figure it out.

Answer
do you have access to a scanner? I would look and trace the harness back under the hood. I had a similar problem with an older GM. I found four broken wires, and it gave no warning. If you have access to a scanner this will narrow some things down for me. Try bypassing the solenoid once again. this will allow the PCM back online.