My 2010 2500hd did that,my battery ground cable was corroded where I couldn’t see and it was loose at the eyelet where it’s bolted to the engine..I have an 05 silverado 1500 HD and my headlight and dash lights flicker like crazy. Just replaced the alternator and battery today but my problem is still there. It does it randomly like one time you will drove and it wont happen the next time it will happen. There is also a loud clicking noise coming from the fuse box under the hood where the drl relay is. I took the relay out and it was still clicking. Please help cause I'm losing my mind on this
have you tried wiggling the wire harness under the fuse box?There are known issues with certain model years of Silverados having significant corrosion under the engine bay fuse block. I would pull yours up and check under it for signs of damage.
Another common element between the 2 systems is the headlight switch, which does sometimes go bad.