My 01 Suburban auto headlight started acting up about like 2 months ago.They would stay on any time the ign was on, even during the day. I swapped out the ambient light sensor and that solved the problem. Mine was only 13 bucks at the dealer. Its GM part number 12450120. This should fit a 99-02 truck or 00-02 suv. 03+ is a different part number. But the installation should be relatively the same on all 99-06 GM Fullsize trucks and SUV's. You will have to take off the top of the dash, its not actually that hard. You will need a 7mm nut driver, a stubby phillips screwdriver, a nylon prying tool (a flathead screwdriver might work, but may also damage the dash)and a hook pick type of tool. First, you'll need to remove the two windsield A-pillar trim pieces(they will just pop off, only held by clips) Now remove the main dash bezel that surrounds the instrument cluster, radio and AC contols. (this will pop right off as well) You will now need to unscrew several 7mm screws along the top of the dash above the radio and instrument cluster. Now pop off the fuse panel cover on the drivers side and also the same panel on the passenger side of the dash. On each side you will need to undo 2 phillips screws (this is where the stubby screwdriver comes to use). Now you pop out the two AC vents on the passenger side just above the glove box.(heres where you'll need the hook tool) After you get the vents out, unscrew a phillips screw in each vent hole. Now look up inside the vent hole and see the release tabs for the "grab bar" on the upper dash. Reach into the vent holes to press the release the tabs that hold the grab bar in, and pull the grab bar straight out towards the seats. Now you should be able to lift up the top of the dash (or completely take it out if you wish) and swap out the sensor. Start to finish took me about 45 mins and that was even with me trying to figure out how to get the dash off. With these instructions, this should be a 20-30 minute job. (vehicle pics are not actually of my truck, they are courtesy of a user on GMT who I helped with his sensor replacement.) Part number... Tools needed, nylon trim removal tool/prybar, 7mm nutdriver, hook tool, and a stubby phillips screwdriver. Remove the windshield pillar trim... Pop off the dash cluster/radio bezel.... 7mm screws to remove... Now pop out the side panels/fuse box cover on each side of the dash and unscrew 2 phillips screws on each side. Now pop out the two passenger side AC vents... 1 screw behind each vent to remove Now look up inside vents holes and push on the white grab bar release button. Pull on the grab bar as you press the relaes button and it will slide out. Now there are 3 clips that pop out above the passenger air bag then the dashboard will lift off, just lift straight up. Now you can remove the sensor from the dash and replace it with the new one. Installation is reverse of removal.