How to adjust parking brake on a GMC Sierra 2500 HD Duramax 4wd?

The adjuster is just like on a car with drum brakes. It can be adjusted with the wheels still on the truck, but if yours is out enough that it doesn't work, an inspection is warranted. Axle seal failure is common and will soak the shoes.

Jacked both rear wheels off ground, and while slowly spinning wheel, tighten the star-wheel adjuster until you just hear and feel brake drums rubbing, then loosened slightly.
There's a plastic dust cover about 1/4" X 1" that you remove, and use a drum brake adjuster tool.

The driverside access hole is below axle, easily accessable. To tighten driver side rear parking brake, turn star-wheel adjuster down.


The passengerside access hole is found above axle, and difficult to see. Removed pass side wheel and used an inspection mirror.
To tighten passenger side rear parking brake, turn star-wheel adjuster up.

Good luck and hope this helps. Oh and the other thing to is that if you do smell axle fluid around the wheels and see oil leaking from the drum area. Then you have a axle wheel seal and or bearing gone bad too.

Hello. I have the issue of the rear seals leaking, soaking the brake shoes. Lot's of fun. I see the star adjuster for the parking brake shoes, but do these auto adjust in reverse with Disc brakes? Also is it possible to install the adjusters backwards. I ended up with no parking brake and the shoes are hardly worn at all. I am replacing the seals and brake shoes as they were coated with oil.

Hi: To my knowledge the rear brakes are self adjusting as the brake pedal assembly has a self adjusting cable mechanism built into it. One thing to try is to reverse the vehicle and pump the brakes, this should adjust the rear brakes if there is adjustment needed there. To test adjustment put on emergency brake.. put vehicle in drive and see if it moves forward while idling. Please rate suggestion... ty