I have a 2003 monte with a 3800. Problems just started last week. When you open the door the interior lights come on as they are supposed to but the set there and blink on and off untill they time out. When you turn the key on the daytime driving lights come on and they will blink on and off about every five seconds. When you turn the headlight switch on, the headlights stay on all the time but the light on the radio goes from dim to bright, dim to bright. I thought that maybe it is the ambient light sensor. I tried replacing relays and it does not have any efffect. Help!

 

BCM (Body Control Module) would be where I would start, because it doesn't sound like a short. I think the BCM is the only link between DRL's and the dome/radio lights...or check all of your fuses first that control those things.