I've been helping my buddy put a new frame under his truck as the old one had rotted away. So the whole cab, bed, front clip, and drivetrain were transferred over to a clean southern frame and were just about wrapping things up. Problem is, when you turn the key, nothing happens. No fuel pump running, no cranking, nothing. First thing I did was jump the starter relay to make sure the starter is good. It is. Replaced the relay, no change. When the key is in the start position, it is sending voltage to the relay telling it to trip but at the same time, something is taking the ground away from the relay, not letting it trip. When the key is off or in the run position, the starter relay has good ground. Similar story for the fuel pump. Has good ground when the truck is off, but in the run/start position gets no ground. If I ground it out somewhere else, it works as it should. If I jump the starter relay with the key on and the fuel pump grounded elsewhere, the truck cranks, gives a sputter or two, then backfires when I let off but will not start. I double, and triple checked that the cab, frame, block, were all properly grounded. My best guess was the Security Passlock not letting the engine run. I tried to do the 10 minute reset deal but the "SECURITY" light turns off after a few seconds and stays off for the full 10 minutes with no change afterwards. Any insight is greatly appreciated as I am really out of ideas as to what it could be. Of all the BMWs and Porches I've solved crazy electrical gremlins in, I didn't think it would be a Chevy Truck that ended stumping me.