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Brake issues

5K views 94 replies 19 participants last post by  JohnL 
#1 ·
I have a 1999 Chevy Blazer zr2 and when I press on my brake 3/4 of the way or when already stopped push it down hard my emergency brake light comes on , but as soon as I let up a bit on the brake the light goes out.

Any ideas on what could be the cause ?

I thought maybe a leak in the brake lines ? Or maybe the master cylinder is going bad ?

I dried the lines off the best I could from the snow and checked the brake lines for a good 2 hours looking for a leak but could not find one or even a line the looked bad enough to be leaking. I also replaced the cap and gasket on the master cylinder just to be sure but to no avail.

Any input is appreciated. Thanks.
 
#3 ·
ummm...did you check the oil level in the reservoir?

as the brakes wear, the oil level drops, due to the calipers being pushed out slightly more then with new pads...there is a sensor on the bottom of the reservoir that reads the oil level...when you push on the brake pedal hard, the level drops even lower, this could be causing it to trip the low oil level sensor

just saying, lots of people overlook the most basic stuff
 
#5 ·
Yes I checked the fluid and no it was not low even with the pedal pressed it was fine. Checked the rear pads when I was checking the calipers for signs of leaks and they still had plenty of pad left.

I also know the rear is disc.
 
#6 ·
My guess would be a leak or perhaps moisture in the fluid. My wifes Bravada (Same Brake system) you can not push the pedal past 1/2 even with worn pads...so if you can push it 3/4 of the way down you have an issue right there.

Another thing that will cause low pedal/spongy brakes is deteriorated rubber brake hoses...they may look good from the outside but they rot from the inside and expand when you press the pedal. That is why braided steel brake hoses give you a firmer pedal.

I would start with the simple and cheap first and flush all the fluid and bleed all 4 corners.
 
#7 ·
brake light come's on when there is a system failure with fluid loss or air at the switch and since your's isnt leaking i would bet you have air in the system paricularly around the porpotining(sp) valve. i would do a fluid flush and bleep the crap out of them like disturban said.

btw my jimmy is the same as disturban's i cant get more than 1/2 way down if i tryed.
 
#8 ·
My DD did the same thing last year and it was a corroded brake lines going to the rear! I'd dry the lines them pump the shit out of them and get out and look to see if there's any puddles or moisture. Then shortly after i had to replace the rear wheel cylinders as well.
 
#9 ·
just a dumb question, does the barking brake still work on this truck? if so push it a bunch of times. if its like the old disc set up that gm used on the camero and such it adjust by running the parking brake regular which no one does
 
#10 ·
Ok. I will bleed them and check the brake hoses and see where that gets me.

The parking brake kind of works. It used to work but after the heater core was replaced the cable from the release handle broke so it is now too short so the parking brake will engage but not stay engaged.
 
#11 ·
John look at your calipers in the rear. if they have the parking brake lever attached centered on the piston then you have to run the levers to adjust them up. if the disc has a hidden parking brake then its separate from the caliper and the lever goes into the backing plate near the axle tube. if so it wouldn't matter because that is separate and has nothing to do with caliper adjustment then
 
#15 ·
I don't think there is a leak because the fluid has never went low in the master cylinder and I would think even with a small leak the fluid level would still drop over time.

Could it be power brake booster ?

This may come off as a complete noob question , but you can't learn without asking.

Could someone identify this for me ?
 

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#17 ·
hey did you ever check to see if the brake light switch was hoding the pedal down part way? pull up on it with your toe and see if makes a click sound? if it does see if the pedal comes back up. if so then its been preventing you from taking in a full charge of fluid at the top of its travel
 
#19 ·
Did you bleed all 4 corners? If so in what order did you bleed them? Did you flush all the old fluid out? When you flush and bleed a whole system always start with the wheel farthest from the master cyl...so bleed in this order, rear passenger, drivers side rear, front passenger and front driver side last.
 
#21 · (Edited)
I would probably be leaning towards a bad master cyl at this point. The booster will either give you boost or not but wont cause the brake light to come on. Bad master cyl will leak a little past the O rings and your pedal will not be as firm and have more travel causing the light to come on. Pretty soon your brakes will be on the floor and you will have to pump them every time you come to a stop. Like I said you should not be able to push your pedal past 1/2 way on those brakes.
 
#28 ·
I had the same problem with my silverado.The only thing that makes the light go on is Either the parking lever is falling down enough to make the light come on or the sensor in the master cylinder is bad.If your fluid is full and theres no ABS light on and the brakes feel good its one of those.Mine was the sensor in the master cylinder
 
#31 ·
you can probably just ignore my last post now lol I didn't read all the way to the end lol

You will still have to bleed all your brake lines after you install the new master cylinder, no matter how well you bench bleed it air will still get in the lines after you actually install it, and your back to square one
 
#30 ·
you'll have to get another person the press the pedal down to search for leaks, a lot of the time the crack in the line will be too small to find just by looking at it, it has to have pressure built up in order for it to leak

there could also be air in the lines, i'd just try bleeding them for a good while first, see if that cures the issue
 
#36 ·
I'm going to bump this because my brakes still suck.

I have meticulously went over every brake line and found no leaks , the master cylinder is new , all the lines have been vacuum bled , the fluid is new , my ABS still works and the fluid in the master cylinder does not go low.

My brakes function but the pedal is soft and I can push it almost to the floor and the parking brake/warning light comes on.

My ABS functions properly and I still have the problem if I remove the ABS fuse.

Help ? Please.
 
#56 ·
I am going to pick up a ABS pump/computer and a booster tomorrow. I think I am going to try and install the booster first because I think it will be the easier job. :sonicjay:

Any other opinions are welcome !



I can always used help. I've never done a ABS pump before and the only time I have done a booster was on 1986 Cadillac Seville.
 
#46 ·
The thing about the booster is that I thought it could make the pedal hard to push if it was bad because of the lack of vacuum. IE why the pedal gets super firm when you pump the brakes with the vehicle off.

I checked the booster the only 2 ways I know how to check it and 1 being to turn it off , pump the brakes up then start it and the pedal should go back to normal feeling. The second way being to have the engine running and slowly remove the vacuum line that goes in the booster and listen for the vacuum sound.

It performed like it should on both accounts.

But if you know of other ways to test it I am more than willing to try it. Since the booster is not a cheap part and not easy to replace either.
 
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