Tuesday, June 29th, 2010 AT 10:46 AM
My four wheel drive service light is on. The switch on the dash does not light up. I am not sure if the 4wd is engaging or not. GM issued a TSB about the connectors and the wiring harness being faulty as well as the speed control sensor. Another issue may be the encoder motor. How can I tell which issue it is without throwing parts at it.