I have a 2004 GMC Envoy, my left headlight recently went out and since I've had it replace my left turn signal only work when my headlights are off (during the day). Does anyone know what this could be?

This may be related, we have the same vehicle and we had trouble with the lights dimming and GM sent us a bulletin that the auto light on and off switch should be switched to manual, maybe this will help you

This may be related, we have the same vehicle and we had trouble with the lights dimming and GM sent us a bulletin that the auto light on and off switch should be switched to manual, maybe this will help you

How do you turn it to manual?