electrical issue

[Artie in Miami]

While changing my trailer light plug, my screwdriver touched the ground pin and the right turn pin (inside the plug) the engine happened to be running so I could identify the wires for stop, turn etc...the instant the screwdriver shorted those two pins, the engine died (no sputter...just stopped). After I finished the wiring, I started the engine and when I put it in reverse (with foot on the brake) the engine died. I disconnected all trailer plug wires, started the engine and was able to put it in reverse without engine dying. Took truck to the store and when I tried to put the signal light on, engine died. When key is on without engine running, signal lights do not work. This has me scratching my head ! When it dies, it will not start right back up...cranks, but won't start...if I let it sit for a few hours, it will start again. 1990 GMC Suburban TBI 350. Bought the truck in 2000 and this is the first real problem in 20 yrs ! I also have a 1986 Suburban 350 4 bbl with towing rear end...I was going to change the trailer plug on that also...but I think I will not !