My brother-in-law has an 06 Duramax with the lesser hp for that year(not sure which one). Well we were driving 150 miles into a 200 mile trip when his whole das went blank. Gauges quit working, radio quit, heater quit, pw and pl quit, interior lights quit, everything quit. Well anyway I told him dont stop and shut it off in case it wont restart and we went the rest of the way back to his place. He shut it off looked at some things and then started it again and now everything works fine and has worked fine for the last couple weeks. Any ideas?? Scared to take any trips with it now... hmmm. He said screw it it goes back as a lease return soon(its outta warranty). tried searching but not very good at that. Ideas????

he has an LLY. it might be a loose ground. they can do some weird things.

Ign switch? Didnt I read about that a while back. Search again with "lly ground", or "ignition switch"