How do I find out if my 06 gmc Denali truck had single our double calipers on the rear

SOURCE: 1999 gmc sierra rear brake trouble

Most likely a the caliper needs to be replaced. Could be more than that though, maybe brake hose. open brake bleeder and make sure you are getting brake fluid from the hose.

SOURCE: cant get rear caliper piston to collapse 06

The rear calipers on that model rotate in, it requires a special tool.

If you pushed too hard directly in, there is a chance that you may have damaged the caliper.

SOURCE: 2007 GMC YUKON denali, rear brakes have an air

Here's a link to a thorough article on the subject which should help you...

http://www.aa1car.com/library/abs_bleeding.htm

SOURCE: I have an 06 gmc envoy denali xl and i'm having a rear end saggin

There is a bulletin for this problem.You have to go to the dealership and have the air spring sensor calibrated.Only the dealers can do this calibration.It does not take long to calibrate a vehicle.Unless they find a different problem.Hope this helps.Good luck.

SOURCE: i have an 06 gmc denali and the traction active

most likely a wheel speed sensor(abs sensor)has gone bad or it is not making a proper connection. you need to take it to a repair shop that has the proper diagnostic tool for it so that they can tell you which one of the four sensors is defective. hope this helps