hopefully it was an air bubble trapped in the system.

 

Its my understanding that the ABS module can not be bled without a scan tool. I tried every way to bleed the system without it but nothing worked. I rented the tool for Advance Auto and it took less than 30 minutes to finish the job. The tool cycles each wheel cylinder from the ABS module and gets every bit of air out. You can look it up on the internet.

Tim

 

Who would have thought a 15 yr old vehicle would have such a complicated brake design.

A few months ago, I replaced a brake cylinder on my 2012 Silverado. Just loosened the bleeder screw and pressed the bake pedal.

It all just makes me laugh and like the H2 all the more.

I checked out my scan tool and found an “automated bleed” function within the brake menu.

While checking that out, I discovered a fault with my front passenger wheel spindle...lol

I plan to r/r in the next few weeks and then get back to my spongy brake issue.

Good thing this vehicle is a toy!

 

The 03 thru 07 H2 have a braking system hearly identical to the GM 2500/3500HD, and is a very capable heavy duty system. It really is not that hard to work with, The thing that really kills these system are not replacing the brake fluid which kills the master cylinder and associated brake parts. The Hydroboost unit itself uses power steering fluid to make it work, many owners never flush and replace the fluid. Also many owners also don't use the correct power steering fluids which can also cause them to start leaking and their early demise.

Rebuilding a hydroboost can be done by a good mechanic but it is tedious and can have many pitfalls. I rebuilt my 06 because it was leaking, it took a good amount of time and effort plus its a messy job and I would not do again. Many people on the forum have replaced seals and have done partial rebuilds just to have them leak or fail within a few thousand or a short time later.

IMO and for what its worth save yourself a great deal of time and effort, replace, the Hydroboost with a new unit (the rebuilt ones seem to have a high failure rate), at the same time put in a new master cylinder, flush your brake system with DOT 4 fluid and rent the ABS OBD2 tool to cycle the ABS and clear any codes once you have everything in place. Yes that will cost you more then doing a rebuild that will be the last time you need to deal with it, not only that brakes are one of those things you don't want to gamble with.