I have a 1993 GMC Suburban. This morning when I started driving, my ABS light came on. The truck also would not shift out of second gea and the speedometer did not work. When I turned around to bring it back home, the CIL came on as well. When I pulled the codes I got code 16, which is the VSS Buffer. After searching through this forum, I decided that replacing the vehicle speed sensor would be a safe bet. So, I drove my truck in 2nd gear to the auto parts store and after about 10 minutes of driving it started shifting normally and the speedometer worked but nthe ABS light remained on. I went in a bought the VSS anyway and figured I would check for a loose wire or something and I would have the VSS just in case. On the way home, it drove perfectly and the CIL and the ABS lights were off. Got home and checked for a loose connection and everything looked great. Drove the truck again and the ABS light came on, it wouldn't shift out of second but the speedometer worked. After a few minutes, it shifted normal again and the ABS light remained on. My question is, could the VSS sensor have an intermittant problem? And, according to the Haynes manual, the VSS is in the transmission. I have a 4 wheel drive and the only thing I saw that looks like the VSS is in the transfer case. Is the VSS in the transfer case on 4 wheel drive trucks?