Hi new here just picked up a 02 denali about 2 weeks ago. I washed the truck last night and now im having issues with the qs. It gets stuck while im turning i get a Service 4ws light in the dash and kicks into 2ws. Im not sure where to begin to start diagnosing the problem.

Sorry to hear that gix...you'll probably have to take it to your local shop or dealer and have the codes read.

Common issue on these rigs is a ground strap located by the spare gets corroded and needs to be cleaned. Does the QS reset when the ignition is cycled?...Welcome too!

I already had the sensor on the bottom of the unit changed about a month ago. The qs worked great untill 2 days ago when it was snowing. The next morning it wouldnt wotk so im hoping its just that ground. Im goin to go check it out now.

Curious if you got your Quadrasteer problem solved. I have the same thing where rears won't return to straight sometimes.