My 1999 Tahoe LT 4WD 5.7L truck had the same problem. My friend, who worked at the dealership, hooked it up to the computer and found out that the lights are hooked, or slaved, to the engine and you can't turn them off without messing up the engine. It SUCKED! But yours may be different, so you may want to get with someone who has the computer and have a look. My Tahoe was originally from Manitoba Canada and the Canadian regulations mandated that the lights had to stay on ALL THE TIME...for safety reasons. So all cars and trucks had that feature and you couldn't turn it off. Here's hoping you don't have that problem. Aloha!