I have a 2014 gmc sierra 1500, its been almost a year since i bought a pair of projector black light head lights. I have came across an issue just las week where the left side drl will not turn on manually or automatically. when locking/unlocking they flash normally, or when using the turn signal the work as well.
i would also smack the headlight and it would come on, but not it wont come on at all just when turning or locking as mentioned before. Not sure if some wiring was messed up or the bulb or connections. bulb is as new as the head lights and no corrosion