02 rcsb silverado, 0411 pcm, 5.3
The port has power during run mode, but when i start the truck my tuner loses power and resets.
the ecm is also finicky about talking to my efilive. starting the truck and shutting it off seems to solve that.

it used to work a while back.
could it be the ignition switch?

 

Maybe. Just jump a 12v hot with key on and cranking to it. Its the red wire. There are 2 grounds as well.