2015 Silverado, 4.3L, a/t, 2WD, 34Kmi. while driving locally (<40mph), stopped for a red light, truck lost ALL electrical power, and shut down. No dash lights, no warning, no physical symptoms. Tried to restart, no-go. Checked battery cables, terminals, all good. Looked for any wiring damage, none found. Checked alternator belt, tight and in good shape Friend came by w/ a jump box (fully charged) , still no joy. Any suggestions?? Truck is driven daily, approx. 60mi/day.

 

I'm having the exact same issue with my truck only mine does it once I turn it off. Did you buy chance find the culprit?