The 1999-2007 classic parking brake design is absolutely garbage. I don't know what the 2007+ models use, but probably the same junk.
I finally fixed it on my 2003 Suburban, replacing one part at a time.
New parking brake pads? Nope, still won't hold.
New disc brake rotor (parking brake drum)? Nope.
New parking brake cables? Nope.
New parking brake lever? Yes, finally works.
It appears the parking brake system in these trucks attempts to auto-adjust (ha!), and to facilitate that, it uses a slipper clutch on the pedal to limit maximum apply force. Over time, that clutch becomes weak, and while it will pull on the cables pretty hard, it doesn't pull hard enough. Going from the old worn out lever to the new one, it was a remarkable difference in force to apply the brakes. I never noticed it getting weak over time, but it definitely did.
My quick test to see if the parking brake system is working adequately or not is to park the vehicle on level ground, set the parking brake, then put the transmission in Drive and Reverse. The vehicle should not move. I don't apply any throttle, just let it idle. When my system was worn out, it would move on its own at idle in gear. Not so with the new parking brake lever.
Now, even with a brand new lever and properly adjusted parking brake shoes, I am not sure the parking brake will hold a truck on a steep hill. The system is anemic. But it is worth a shot.
2003 GMC Sierra 2500HD LB7 Duramax 4WD Crew Cab SB
310k miles. 8,260 lbs empty. Built motor, and still slow.
2003 Chevy Suburban 2500 LB7 Duramax AWD Quadrasteer
135k miles. 6-speed Allison conversion. Quadrasteer 4-wheel steering.
1982 Chevy C10 Silverado 6.2L Diesel RWD Single Cab LB
115k miles. Built 700R4 automatic, 4.11 gears.
Cheap bastage -- guilty as charged. ~~ TheBac
If you try Pee in the urea tank, Ur ine for big problems. ~~ heymccall