Parking Brake control module

[Larryjb]

(control module, that's what they call it in the service manual)

I'm used to these parking brakes ratcheting as you depress them. Were they supposed to ratchet in 2002?

The cable between the release handle and parking brake module has broken. I'm trying to decide whether to replace the entire module (about $50 for ACDelco), or just the handle/cable (so far, about $20). It's not much more for the entire module, but it's a fair bit more work to do the module than just the release cable.

I'm also not convinced the autoadjust mechanism has been working, but I've read that sometimes it needs to be reset. I did have to replace my intermediate cable a couple of years ago.

 

[OR VietVet]

On my 2002 there is no ratcheting. I would just do the handle and cable. The shoes for the park brake can be adjusted after pulling the rear rotors but they hardly ever need adjustment unless you accidentally drive with the park brake on. The adjusting mechanism can bind or freeze up with age as well or rust. I recently did mine. It was not that much work and I did rear pads at the same time.

 

[Larryjb]

Thanks Ron,

I had adjusted the rear parking shoes so that I could just slip the rotor back on. I also removed the rust ridge with a file. As a result, the parking brake did work, but the pedal would go to the floor so I don't think something was done right.

As I said in my original post, I had replaced my intermediate cable because it broke. However, I also suspect that I didn't set up the autoadjuster correctly at the time and I'm now thinking that's why my pedal was going to the floor.

Is there any chance I wrecked the auto adjuster? Do I just need to set it up again? The service manual says to pump the parking brake 3 times until it auto adjusts, but that didn't work either.

 

[OR VietVet]

The auto adjuster will be in with the shoes, like the self adjuster for rear brake shoes would be. Will look like this: https://www.rockauto.com/en/moreinfo.php?pk=904564&cc=1380372&jsn=2266&jsn=2266


When you filed the rust ridge and installed the rotor there seems to still be too much travel before the shoes contact inside at the rear rotor/drum combination.

You could have that little drum section machined and clean the shoes and make sure the adjuster is free and lubed and then get a tighter fit.

 

[Larryjb]

Our parking brake modules have an auto adjust for pedal height as well as the adjuster at each wheel. It is meant to take up some of the cable slack. I don't think many DIY know about it unless they have and read the FSM for the parking brake.

 

[OR VietVet]

I would almost bet that the adjustment for pedal height and at each wheel is just a fine tune adjustment, so to speak. The initial main adjustment needs to be done at the adjusters at the rear park brake shoes. I could be wrong but I am going to stick with my gut feeling on this.

 

[swathdiver]

Thanks Ron,

I had adjusted the rear parking shoes so that I could just slip the rotor back on. I also removed the rust ridge with a file. As a result, the parking brake did work, but the pedal would go to the floor so I don't think something was done right.

As I said in my original post, I had replaced my intermediate cable because it broke. However, I also suspect that I didn't set up the autoadjuster correctly at the time and I'm now thinking that's why my pedal was going to the floor.

Is there any chance I wrecked the auto adjuster? Do I just need to set it up again? The service manual says to pump the parking brake 3 times until it auto adjusts, but that didn't work either.

Sounds like you did what I did. Before working on the shoes out back, did you disable the parking brake actuator? We're supposed to pull the foot pedal all the way up and insert a screwdriver into a hole in the side of the unit while someone else pulls the main cable underneath the truck rearward so the holes line up for the screwdriver. I didn't know how to do this. My parking brake holds but goes mostly to the floor with new shoes.

Speaking of shoes, you know how much clearance is supposed to be between the shoe and drum? A quarter of a millimeter! I bought a brake shoe caliper to measure mine. I need to take it all apart and reset everything proper too. Come on over to my house and we'll get it done!

 

[Larryjb]

I had already adjusted the main adjustment at the wheels tight enough that I could barely get the disk back on. I did the same method on my wife's Explorer and the pedal is firm and very little travel in the parking brake pedal. In my Tahoe, the pedal would go straight to the floor before the brake would hold. It's my understanding that most of my pedal travel has been taking up slack in the cable.

I will take a closer look this weekend at the mechanism, if possible. I understand that it is possible that the autoadjuster is disabled:
https://www.gm-trucks.com/forums/topic/97978-parking-brake-adjustment/

 

[swathdiver]

I had already adjusted the main adjustment at the wheels tight enough that I could barely get the disk back on. I did the same method on my wife's Explorer and the pedal is firm and very little travel in the parking brake pedal. In my Tahoe, the pedal would go straight to the floor before the brake would hold. It's my understanding that most of my pedal travel has been taking up slack in the cable.

I will take a closer look this weekend at the mechanism, if possible. I understand that it is possible that the autoadjuster is disabled:
https://www.gm-trucks.com/forums/topic/97978-parking-brake-adjustment/

There's another thread over there with pictures, again a guy with a Duramax doing the job. For some reason, it's been very difficult for my brain to understand how to do this properly!

 

[Larryjb]

Sounds like you did what I did. Before working on the shoes out back, did you disable the parking brake actuator? We're supposed to pull the foot pedal all the way up and insert a screwdriver into a hole in the side of the unit while someone else pulls the main cable underneath the truck rearward so the holes line up for the screwdriver. I didn't know how to do this. My parking brake holds but goes mostly to the floor with new shoes.

Speaking of shoes, you know how much clearance is supposed to be between the shoe and drum? A quarter of a millimeter! I bought a brake shoe caliper to measure mine. I need to take it all apart and reset everything proper too. Come on over to my house and we'll get it done!

James,

I'm starting to understand now, I think.

When doing the shoes, they need to be adjusted to spec as you say. However, if you do a complete job by replacing the adjuster in the wheel, removing the actuator the connects the cable to the adjuster, you will have to introduce slack into the cable to get it hooked back up again. When you get everything put back together, even if the parking brake shoes are adjusted right, there will still be slack in the cable that is very difficult to remove. Even if you tighten things up at the equalizer, you may not be able to tighten it correctly.

By releasing the tension at the pedal by inserting the screwdriver, you can do all the work in the back without undoing the equalizer. Then once you have everything done in the back, making the sure equalizer is tightened to the specified torque, the autoadjuster will remove the remaining slack in the cable.

I'll look for the other thread you mentioned.