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I was driving on a snow covered farm road when I locked the wheels activating the abs. I noticed the pedal went down slightly more than normal,but the truck stopped well. About a mile later on paved roads I found I had absolutely no brakes. It’s not like a bad brake line where you have low pedal. I have no pedal pressure, no red brake warning light and no abs light. The warning lights do work when you first turn on the ignition. The master cylinder doesn’t appear to have lost fluid and I don’t see any leak under the truck or around the master cylinder. The truck is a 2003 Chevy Silverado 2500HD with hydroboost power brakes. It has about 130k miles and has never even had a bleeder opened. The truck routinely sits for a week or so, then handles severe service with no problem.
Although I have seen many brake failures, I have never experienced this. Is it possible to loose both chambers of your master cylinder at the same time? Can something come disconnected in the hydro boost unit? Can something go bad in the abs and cause no pedal? To say It was scary doesn’t cover it. Any info or ideas would be appreciated.
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If the hydroboost failed your pedal would be hard, just like if the engine wasn’t running. It is possible to blow both circuits at the same time in your master, but not something you see every day. I’d start by seeing if it will push out fluid. Start going through the bleeding just to see if it will actually push out fluid to the wheel end. This is certainly a weird one. I can imagine the look on your face when that pedal went to the floor.
Also check to see if the pushrod going into the master from your brake pedal somehow got unhooked. Sometimes its the little things that get you.
I’ll check that tomorrow when it’s light and I can get the barn heated up. It’s too damn cold here tonight. I can’t see it pushing out any fluid because it has no pedal at all. It does feel like the pedal is still connected to something, but I haven’t actually looked at it yet. I was kind of busy changing my shorts when I got home.
Just thought I would report back on my brake failure. It turns out I blew out at least two lines at the same time. The lines on this truck are routed together behind the left front wheel in a plastic clip. This catches all the road salt, holding it there. The result is a bad spot on all 5 lines. I think when I activated the abs the pulsing blew out the lines without an unbalance between the front and rear chambers. The red light did come on during the bleeding procedure, so it does work.
That is a scary proposition indeed. I’m glad you found the issue. It’s odd that 2 lines went out at the same time and would account for the complete loss of braking. Makes sense with their position and corrosion being a factor. When the ABS activated there was a LOT of high pressure in the lines as that is how the system works. Makes sense that it would blow then but it’s damn inconvenient that it happened shortly after a panic stop. HUGE safety issue if you asked me. I’m glad you’re OK and so is the truck. Thanks for keeping us up to date and for using the ETCG forum.
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