If you are asking about the high beam headlights you either have burned out bulbs or the switch that turns the high beams on has failed. If you are asking about the high beam indicator on the dash I would also think it no longer works account it has failed.
Bad bulbs Bad dimmer switch
High and low beams have differant filaments. You have to replace the bulbs.
As a guess both low beams are burnt out The daytime running and high beams are the same light filament. Or the fuse or the relay for the low beams.
Your computer brain in your truck is messing up take it to a mechanic is my advice. Not sure I even understand what you are asking,but, If its what I think , its just a matter of turning on your lights. For some reason Chevy thought it would be a good idea to have just your low beams and the high beam dash light come on automatically when it got dark, don't ask me why. If this is not it rephrase you question and be more presice.
Yes
dimmer switch wore out or you might just have running lights.
your bulbs are burnt out. when you switch on the high beams its only the high beams. but when you flash your brights it lights up both high and low beams.
No, it does not. I have seen after market kits that allow all 4 lights to be on when using your high beams.
These lights have 2 different "lights" in each of them. This occurs frequently. Change out the bulb and everything will be working fine once again.
Your high beams work but your low beams do not because the switch is broken that switches between high and low beams. Electrical switches wear out.
the fog lights work with the low beams , they wont come on with the high beams
Have you checked the drl relay?