04 4runner brake help.

[bearfutedninja]

My 4 runner started making a buzzing noise all of a sudden. brake light came on and the pedal is very hard if you press it it barely stops. anyone have an idea what the hell it is.

 

[kdavis1984]

Vacuum leak?

Specifically the vacuum line coming off of the brake booster on the firewall.

 

[bearfutedninja]

i see the booster. not seeing vacuum line i see about 5 electrical connections and break hard lines. i could be missing something let me go recheck.

 

[Ben Segrest]

brake booster issue. could be as simple as a vac line or could be a problem with the booster itself.

 

[Ben Segrest]

i see the booste. not seeing vacuum line i see about 5 electrical connections and break hard lines. i could be missing something let me go recheck.

I was wondering as I was typing whether it would have a vacuum booster or an electric one.

 

[kdavis1984]

brake booster issue. could be as simple as a vac line or could be a problem with the booster itself.

I was leaning towards the line because he said the noise its making. Never thought aboutbthe booster itself. Thanks!!

 

[bearfutedninja]

Pic of it

 

[kdavis1984]

Are you hearing the noise while its running and the hood is up? Or only when you press the pedal?

 

[kdavis1984]

That picture looks like you are looking at the master cylinder. All the hard lines are for each wheel (4 wheel disc) the booster should be behind that, huge, round, black. Mounted on the firewall

 

[bearfutedninja]

its an alarm sound coming from under dash sound more like a bomb about to go off.

 

[kdavis1984]

It must be electric like Ben was thinking. In that case im not sure. Was hoping it was just a popped off vacuum line, easy fix. Good luck, hope it does turn out to be simple

 

[CrkdLtr]

It almost sounds like the ABS motor is engaged, explaining the noise and hard pedal. Possibly one of the ABS sensors could be loose? Try disconnecting the battery for 10 or 15 minutes to let the computer system discharge. Hook back up and see if noise still there and pedal hard.

Did you have a brake job or any suspension work done recently?

 

[bearfutedninja]

The noise comes on about a second after you turn the key and when you start it. It doesnt stop until you turn the key off

 

[bearfutedninja]

And no work has been done to it lately. we have had a bit of bad weather lately i thought it could possibly gotten some water where it wasnt supposed to be.

 

[Charles1959]

I'm thinking that the ABS motor is running constantly, try to build up pressure in the accumulator. The accumulator normally has about 2500 lbs pressure in it and it seems for some reason the pressure isn't building up. I don't believe there is a vacuum booster on this brake system and that all assist comes from the accumulator. From the pic it appears that the front of the reservoir and the fill cap have had dirt knocked off of them recently as if fluid was added. Did the fluid level get low enough that air entered the system? Air in the system will prevent it from building enough pressure to shut off as it is designed to pressurize fluid, not air. The whole brake system may need to be bled, best done by pressure bleeding. NOTE: BEFORE SERVICING AN ABS BRAKE SYSTEM YOU MUST BLEED ANY PRESSURE OFF THE ACCUMULATOR BY PRESSING THE BRAKE PEDAL DOWN ABOUT 20 TIMES WITH THE IGNITION KEY IN THE OFF POSITION!! This pressure stays high even when the car is turned off. Even if the system hasn't built up enough pressure to shut the motor down you still could have well over 1000 lbs pressure in the accumulator. If you crack open one of the lines you could have brake fluid injected through your skin if the pressure isn't bled off first. That would make for a nasty medical problem. Look up the brake bleeding procedure for your vehicle.
Now, if there is no possibility of air getting into in the system, you probably have had a hardware failure and I'd get it to a good mechanic. ABS brakes are complicated.
Good luck with it!
Charlie

 

[jimdana1942]

There should be a fuse for the ABS system. If so, unplug the fuse and start up and test your noises and brake pedal then. But don't drive like that.

 

[CrkdLtr]

There should be a fuse for the ABS system. If so, unplug the fuse and start up and test your noises and brake pedal then. But don't drive like that.

That has got to be the most on topic and coherent post I have ever seen you make...

 

[jimdana1942]

That has got to be the most on topic and coherent post I have ever seen you make...

I'm coherent on serious topics. Otherwise, I consider it a free for all

 

[bearfutedninja]

No fluid was added. It actually is over the full line. i think it is high because the brake pedal is probably down causing the fluid to go into the reservoir.