Braking system became increasingly low?

Tiny
RED CLIFFORD
  • MEMBER
  • 1997 CHEVROLET 1500
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 150,000 MILES
Brakes became increasingly low. I changed the master cylinder twice with new ones and replaced the brake booster with a new one. I have bled the brakes three times and still have no brakes. Tried to bleed the ABS valve also but still nothing?
Tuesday, March 10th, 2026 AT 4:47 PM

4 Replies

Tiny
CANNON1349
  • MECHANIC
  • 888 POSTS
Hello, did you bench bleed the master cylinder?

William
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Tuesday, March 10th, 2026 AT 5:07 PM
Tiny
RED CLIFFORD
  • MEMBER
  • 2 POSTS
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Tuesday, March 10th, 2026 AT 5:11 PM
Tiny
CANNON1349
  • MECHANIC
  • 888 POSTS
Just to be sure, the master cylinder needs to be bench bled and then installed without introducing air into the system. The wheels must then be bled in the order of LF, RF, LR, RR. Then the ABS module can be bled with a GM appropriate scan tool or you can bleed it by removing the cap on the side of the unit and pressing in the needle, then have someone step on the brakes. Doing it the normal way will not allow the air to be forced out. After this bleed the wheels again in the order of LF, RF, LR, RR. If you can repeat these steps and let us know how it goes. Also take note that some trucks have two ABS valves to bleed.

William
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Tuesday, March 10th, 2026 AT 5:19 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 55,090 POSTS
You may have a sized caliper slide which will make the brake pedal low, please go over his guide which will help you fix it.

https://www.2carpros.com/articles/discover-why-automotive-brake-pads-wear-unevenly

Also, did you use a scanner to open the valves in the ABS unit to help get the air out? Please go over this video to see what I am talking about.

https://www.youtube.com/watch?v=nQRnKyVyMuQ

Please go over these guides and get back to us.

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Wednesday, March 11th, 2026 AT 8:36 AM

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