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GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29396
Experience:  GM Grand Master Technician 2007. 14 years experience.
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I have a soft Brake Pedal on a 2004 Trailblazer LS 2wd... I

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I have a soft Brake Pedal on a 2004 Trailblazer LS 2wd... I replaced the Master Cylinder and have the same pedal feel??? help?

Welcome to Just Answer and thank you for asking your question. I look forward to helping you fix your vehicle.


I will try my best to help you and in order to do that, I need you to describe the issue in as much detail because I only know as much about your vehicle as you have told me in your post, so my answer will be based on what you have posted. Please include all the small details that may seem insignificant such as warning light, codes that you have scanned and how this started.


My goal is your satisfaction and I ask that you not accept unless you are satisfied, but if you are satisfied, please accept so I can receive credit for my work and time. Positive Feedback is greatly appreciated and bonuses are always welcomed.


Please feel free to reply as needed.


Was there a leak prior to the master cylinder leaking?

Did you perform the ABS system bleed?

Customer: replied 7 years ago.
The truck is my wifes and has always had a softer brake than my TB SS... There is NO brake warning light on nor any codes. It feels too soft and if you stop hard it does not "grab" the way it should. I understand my TB SS has monster brakes in comparison but there is no way even if you disabled the ABS could you get the brakes to lock up.... simply not enough pedal left. Once appplied firmly there is maybe a half inch of pedal left and it can easily be put to the floor.

OK, that is great information. Lets perform a check. Using a tape measure, we need to measure the travel. with the engine off, press and release the pedal 10 times fully to use up the reserve. Then hood the tape on the top of the pedal and measure to the steering wheel. Next apply about 100# XXXXX force on the pedal and measure again. Do this 3 times and post the average distance of travel.

Just for comparison in pressure do your TB as well.

GM Tech (Cam) and 6 other Chevy Specialists are ready to help you
Customer: replied 7 years ago.
I will reply to you in about one hour... I am at work and the truck is at home... Thanks.
SOunds great.
Customer: replied 7 years ago.

Ok sorry for such a delay....


Trailblazer Average pedal travel engine off afer ten pumps of the pedal = 2" TBSS same test 2" as well.

I preformed the same exact test with the engine running and found the Trailblazer at 5 1/2" average and tghe TBSS only 3 1/2". If I apply greater pressure to the TBSS the pedal remains and is solid the Trailblazer goes and additional 3/4" and does hit the floor.


I bled the four corners I did NOT do an abs bleed... how do you? do you have procedures for that?


Thanks for your help. :-)



Rob, ok, give then not running test is the same indicates there is no air in the lines. So this means this is something to do with the rotors and pads. Excessive corrosion, sticking slides and so on will cause this. Have a close look at all the brakes, all the way around.
Customer: replied 7 years ago.
Thank you.

I will inspect the brakes all around