headlights glitch

[jd hauler]

My buddy has a 2000 silverado and has a problem with the headlights and dash lights with a blink to them, they dont go completely out, but seems like a slight glitch somewhere, does anybody have any ideas? oh yeah its a 1500 extended cab with a 5.3, also have an annoying belt chirp.  thanks

[TROYROBO]

check headlight switch--already replaced mine when cluster lights went out because of faulty switch---it is simple to check--if you have to buy new one -it is only 40 bucks at dealership---my 2 cents--  might help you-- :thumb:      

[Bish]

My tahoe has done it off and on for 85k.  Put in an Optima at 20K, and an alternator at 80K and it still does it sometimes.  I drove around with an alternator in my truck cause I thought it was the source of the problem.  Voltmeter also ticks lower for an instant when the lights dim like there is a short somewhere.  How do you test the headlight switch?