First i want to open with a THANK YOU to @TinkeringFox and @pgamboa for all your help on this.
OK so i have a 2017 1500 Denali and i have been wanting to get rid of the 12V chargers up from (what am i going to do with 3 of them plus 1 in back seat???)
so instead of paying 100 bucks or so for the OEM switch i got a 22mm momentary switch for 8 bucks and installed it instead of one of the cigarette lighters up front.
I then used the harness from @pgamboa but hooked it up to the switch instead of the OEM headlight switch.
i used the ground wire from the 12V charger, spliced it to the neg of the indicator LED and the common leads.
the N.O. lead (switch output) wired to X5:5 of the BCM (Gray wire) and from the BCM (X1:12) back to pos LED indicator lead on the switch and spliced as trigger wire to the light bar relay.
now i just need to decide which light bar will fit my Denali grill with active shutter vents.
it's not alot of room but it has been done with some minor trimming. probably a single row curved bar.
if anyone has recomandations please share