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  1. #1

    Exclamation Brakes what brakes.

    So the brakes on my truck are for no reason not working right sometimes when I step on them the slow down my foot goes all the way to the floor before I begin to slow. I think it might be my brake booster or vacuum because the brakes are fairly new they we totally redone May of last year with ceramic pads. I need ideas soon ecause it is very scary getting off an exit and having your petal hit the floor efore you start to slow.

    1996 Chevy Tahoe LT 5.7L V8 4X4 205,000+ miles. Built proudly at Janesville Assembly in Janesville, Wisconsin
    Basic mods: Lights all over, bunch of electrical work, and a couple cooling mods.

    Check out my other mods in My Garage:

  2. #2


    I would first check the fluid level. If it is low then I would start looking for leaks. Next, I would checkout the master cylinder, specifically where it mounts to the brake booster. Look for fluid running down the booster. Also, crawl under the dash with a flash light and look at were the rot goes from your brake pedal thru the fire wall. I have seen master cylinders fail and let fluid run back thru the booster, ruining the booster. Every time that I have seen a booster fail it has made it hard to push the pedal down, not send the pedal to the floor. I suspect that you have a leak somewhere (maybe a rear wheel cylinder) or your master cylinder is failing.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors,
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  3. #3


    Yes the booster normally makes it hard to push the pedal, it stops assisting you to overcome hydraulic pressure.
    As Pikey posted a leak would be the first guess, should be easy to tell if your missing brake fluid.
    A leak will also draw in air to the system and aggravate things.
    Another possibility is a failing master cylinder.
    Do you have ABS? Because this system could bring a few more items requiring troubleshooting.
    Im not advocating continuing driving the truck, this places other innocents in jepardy as well as yourself, but if you end up in a situation keep in mind you still have a cable actuated park brake, awkward to activate while driving and only aactivates the rear brakes but in an emergency itll stop you, just takes a little more room.

  4. #4


    The brake fluid is at normal levels and there doesnt seem to be any fluid leaking, currently the brakes do work fine just I have to leave more room to brake because it takes longer. I do have ABS but I have an ABS code that isnt letting the system work. (left side speed sensor is dead) I will price out both a new booster and master cylinder.

  5. #5


    Look into that ABS system a little more.
    Whenever I run across a vehicle with brake issues and ABS Im always suspicious of the ABS, it changes a simple hydraulic system into something much harder to troubleshoot and maintain. Left side sensor dead could have become more of an issue, just because it isnt supposedly working doesnt mean it isnt exerting influence over the hydraulic system.

  6. #6

    Join Date
    Jun 2006
    River Ridge Louisiana-4 miles W of New Orleans-didn't flood-water stopped 800 yards away.


    Exactly as TBPLUS10 said
    When my booster went out- it felt like the pedal took 10x the effort to move
    Yeah-close to impossible to get it to the floor.
    And I actually could hear a hissing air leak kinda sound
    I was broke-so drove around for 10 days with a bad booster- had to keep my speed waaaay down-and get on the brakes WAAAAY early.
    1998 suburban-
    1/2 ton

    199500 miles

  7. #7


    I would also check into the ABS system. You can unplug the ABS pump and it should completely shut down the system reverting it back to a normal hydro system.

  8. #8


    Doing so won't damage the ABS components correct? Last this I need is more ABS problems. BTW how do I trouble shoot all of this, currently the truck is at camp with me and I won't be back home until next Monday night. I want to know if anything is up before I go in next Tuesday to get my new tires and have my steering aligned. So if I need something replaced I can do it or have it done while my tires are done.

  9. #9


    For the master cylinder you just need to look for leaks. I really think that it is an internal issue with the master or the abs kicking in. It seems like you have a leak somewhere, whether internal or external. You can have an o-ring blown out on the piston inside the master causing the fluid to flow passed it. I know that with my abs system that I can just unplug the pump and the light comes on, but it basically turns the system back to an pre abs system, complete with wheel lock up. My dad had an issue with a sensor on his Avalanche and we just unplugged the pump. It stops just fine now. Unless or course you are on ice.

  10. #10


    Today after lunch I'm going to trouble shoot with the truck. IIRC there is two wiring plugs in my ABS pump, so should I remove and tape off both? Also what other steps should I follow to trouble shoot? I personally think its an internal issue with the master because 6 months before I bought the truck it blew a rear brake line and only had fronts until right before I bought it when they got it fixed. He didn't drive it like that long, but it still would put extra strain on the front brake system. Right now I think the truck is using mostly rears because the front cylinder is leaking.

    - - - Updated - - -

    Definly is not the ABS because I pulled the ABS fuse and the braking is the same. I decided that trying to pull the 5+ wiring harnesses from the pump was a bad idea so pulled the fuse. The truck brakes OK but it needs extra room so I'll have to drive extra cautious tonight and on the high way home.

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