Quote:
Originally Posted by RemyRunner
I posted a question about a squealing in another thread that I am encountering and through some digging, I think it might be the same? I took a video of it when depressing the brake. Could someone verify if they have the same thing and then i will continue down the path of trying to find an ABS accumulator:
https://www.youtube.com/watch?v=onRasZ_XZy8
Thanks guys.
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It's hard to tell from your video, but I'm guessing it's the electric motor part of the ABS/booster assembly that is making the noise not the accumulator which wouldn't make any noise.
How the booster system works is there's a small electric motor which powers a pump which builds up pressure which is stored in the accumulator, that pressure assists your foot pressure when braking thusly applying more pressure to the master cylinder than just your foot power could, the same pressure is also used by the ABS system when it activates.
Now that all being said this is what triggers the electric motor to power on, when the pressure drops to a certain level the motor comes on, normally it can be heard inside the vehicle seemingly coming from behind the instrument cluster but it's just a slight buzzing sound, it usually comes on when switching on the ignition after the vehicle has sat over night or for an extended time period and also after 3 to 4 depressions of the brake pedal, this is all normal, if you noticed you had to depress the brake pedal 3 to 4 times then you heard the squeal, again normal...except the squeal...what I think you're hearing it something is worn out within the motor and it starting to "drag", it could be the brushes, armature or a bearing.
The motor can be replaced without replacing the entire assembly, to get another motor read my post...#2... in this topic if you need to replace it.
Now you need to do a little more investigating, go to your local auto part store and buy a "mechanic's stethoscope" for about $10 or so, it looks just like a doctor's stethoscope except it has a long metal probe on the end used to touch areas when trying to pinpoint noises, then locate the electric motor on the master cylinder assembly, turn the ignition "on" but don't start the engine have someone depress the brake pedal several times until the motor kicks on while you are under the hood with the probe on the motor, you should hear the squeal loudly with the stethoscope if it's the motor, the electric motor/pump/accumulator assembly is on the passenger's side of the master cylinder at the back and underside.
I'll try and post a photo of the motor and pump assembly without the accumulator so you can see what it looks like, you can clearly see the wires coming out of the motor, the motor has a silver housing but your's is most likely has a black housing, the accumulator is a canister looking device that will screw into the plugged hole at the top left in the photo of the motor/pump assembly, I'll also post am exploded image of the entire master cylinder assembly, the motor/pump/accumulator is on the left.