Low brake pedal?

Tiny
FGR8FRK
  • MEMBER
  • 1997 CHEVROLET TAHOE
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 150,000 MILES
Working on my daughter's SUV listed above. She had someone put new front rotors and pads previous but stated the pedal had always gone way down ever since she bought it. I adjusted the rear brakes which were in good shape and proceeded to bleed them out rr, lr, rf, lf. Although the pedal improved, it still went way down. After bleeding several times and no improvement, I ordered and installed a new master cylinder. After bench bleeding and installing, I again bled all the brakes and there was no improvement. I had read a couple of threads about running it on gravel and sliding the front wheels to get the abs to engage, I did this multiple times with the abs engaging each time and the pedal still goes way down. I have a friend that has a scan tool to do an ABS bleed but should what I did on my driveway helped at all?
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Tuesday, November 29th, 2022 AT 11:45 AM

5 Replies

Tiny
KEN L
  • ADMIN
Not really because the air is still in the ABS module, the valves need to be open when the bleeding is being done.

This video will show you how:

https://youtu.be/nQRnKyVyMuQ

This guide may help as well:

https://www.2carpros.com/articles/brake-pedal-goes-to-the-floor

Please let us know if you need anything else to get the problem fixed.

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Tuesday, November 29th, 2022 AT 4:09 PM
Tiny
FGR8FRK
  • MEMBER
Okay, so I was able to use a Snap on Triton D10 to run an automated bleed, now unlike the video you provided (thank you) which was on a ford F150, it did not ask me to open a bleeder. I ran this about a dozen times and at the end had a much better pedal with engine off, but when I started it although the pedal was a lot better it still felt spongy. So, when my wife came home, I went around and bled them all several times thinking it pushed air from the module into the lines, although with the motor off the pedal is pretty decent, now when I started the pedal is back to going way down.
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Monday, December 5th, 2022 AT 11:27 AM
Tiny
KEN L
  • ADMIN
Sometimes the pedal can feel mushy or low but when driven the pedal will operate normally. Does this tahoe have drum rear brakes? If so double check that the shoes are adjusted correctly. You need to bleed the system with the scanner opening the ABS valves (all). Let me know.
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Tuesday, December 6th, 2022 AT 12:33 PM
Tiny
FGR8FRK
  • MEMBER
Hello, So I've tried every way in the world to bleed these brakes. It does have drum brakes and to be sure I have them over adjusted tight so that it removes it from the equation. I purchased a Motive pressure bleeder and bled the system with it, I barrowed my friend's computer again and did the automated bleed with the pressure bleeder setup attached. It still has a better pedal like before after the auto bleed but if I manual bleed after, the pedal is not as good, but if I run the auto bleed it's better again. I have watched a few videos and 1 talks about a faulty or stuck partially open valve in the BPMV, could that be possible? And if so, in case I can't find the exact unit as a whole, can the control module be bolted to a replacement BPMV? I appreciate your time, thank you.
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Sunday, January 22nd, 2023 AT 11:14 AM
Tiny
KEN L
  • ADMIN
If all of the air is out of the system it might be the brake master that is bad, but I have to say these trucks have a mushy pedal, it could be normal. When you bench bled the master did you get all of the air out? Please watch this video to see what I am talking about:

https://youtu.be/WDxvEQrMkBg

Check out the air coming out of the fluid holes in the fluid reservoir.

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Monday, January 23rd, 2023 AT 11:15 AM

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