Hey guys, sorry if I'm making a repeat post. Just got an 04 Trailblazer a few days ago. Start it and let it run this morning for 5-10 min with 10F weather outside. Switch to a4wd and the light comes on, but the selector light is solid. Drove it half an hour to work, switching between 4hi, a4wd, and 2hi while driving and in park. The selector showed it engaging each time but service light remained on. After I got to work, I shut the truck off and started it and the light was gone and the selector showed engagement. There was patchy ice/snow and I didn't slip but couldn't tell if it was for sure engaged. Any ideas?