4wd low

The only way to turn on the 2005 Tahoe is by remote access and placing the key in. Everything is fine when it turns on. The moment I press the brake to put it in drive, the brake light on the instrument panel turns on, 4wd goes to the lowest gear, and the air conditioning turns off. Already...

I test drove a 09 Tahoe LS 4wd. When I put it into 4 low, the traction control light come. It shifts into 4 low after about 5-7 seconds. It jerks and when I take my foot off the escalator it feels like the truck falls on its face. Please help. I traveled 5 hours to look at this Tahoe and need to...