[Andy1]

Guys, your HID bulb is failing. Best to just replace it. It is covered under warranty.
The ignitor ballast is trying to re-ignite bulb, then the ballast over heats and turns off. Turning off car re-sets ballast only to start cycle again. The ballast is very expensive (over $800) so best to change bulb now.
Its about 2 hours to change bulb, and bulb is about $75 to $120 each depending on where you get it.
Fender liner and bottom pan have to be partly undone to access fasteners behind lamp housing. Airfilter box etc has to come out to access more fasteners. Way more complicated and time consuming than needs be. GM are you listening??
Good luck