This is a nice video showing how to remove and reinstall the parking brake module:
If you look closely at his parking brake module at exactly 3:00 minutes, you will notice a similar crack beginning in the same place mine cracked. This is obviously a weak point. His hasn't cracked through, but mine has. At 3:56 minutes you can see the new one with no crack.
This may be something you guys want to inspect, especially if your parking brake pedal is going to the floor.
I'm not sure if this is related to the function of the auto-adjuster for the pedal height. It is entirely possible that I didn't have the equalizer adjusted right either, resulting in the inability of the auto-adjuster to remove cable slack.
There are three adjustments for the parking brake:
1) Adjust the equalizer nut to 31 pound inches. This remains a little unclear to me. I'm assuming that the torque will increase as the tension of the cable increases so that by the time you achieve 31 pound inches, you have the right amount of tension on the nut. However, if the threads of the bolt from the intermediate cable are even slightly dirty or rusted, this torque is meaningless because you will get to 31 pound inches before any slack is taken up. From the video above, GM has a new intermediate cable with no bolt, so there is no adjustment to worry about here.
2) The star adjuster which adjusts clearance of the shoes to the inner drum of the disk. This should be 0.026" or slightly less than 1/32". Most people adjust this by making sure there is no rust ridge in the drum part of the disk, then adjust the shoes so that the disk can just slide on. I achieve this by expanding the shoes until I couldn't get the disk on, then backing off the shoes until the disk would go on. Then I'd apply the parking brake and release and recheck the fit. Often I'd find I could expand the shoes another few clicks. In the end, I had the shoes adjusted so that the disk would just slide on.
Note: the instructions for my trailer brakes say that the shoes should be adjusted so that they just barely rub as you turn the wheel.
3) The last adjustment is made once the primary tension of the cable is set in Step 1, and the shoes are adjusted in Step 2. This last step is designed to take up the remaining slack on the parking brake pedal. There is a spring that is designed to apply the right amount of tension in the parking brake pedal. If steps 1 and 2 are good, you should get just the right pedal height by applying and releasing the parking brake 3 times.
At least, this seems to be what is happening in theory with the adjustments. Given that my parking brake module has a crack, I won't be able to test this out until I get the new one installed and try to adjust the equalizer as properly as I can.