Possible ABS sound

[lugueto]

I posted this in Yotatech without any response

I have a 2007 V6 4runner Limited 4x4, it started making a noise a while back that has been bugging me. Im suspicious of the ABS system

Everytime you start her up, get her into gear and start moving, about 10 seconds after you get going you get a buzzing sound, very similar to the ABS acting up, which lasts only for a couple of seconds. She doesn't do anything else, no noises, no vibrations, nothing. It only happens after you start her up, you can stop and go all you want and she wont do it again. Everything works perfectly fine: brakes, transmission, everything is in good nick, no weird malfunctions from any system

Any ideas?? Has anybody else experienced this?

Thanks for any help,

Luis

 

[NoWayOut]

Its normal, you'll forget about after awhile. I think it is just the brake system charging up the pedal or something like that.


.

 

[cloudrunner]

Mine started doin it around 80k miles.

 

[Kmvreter]

Its normal... it is just the brake system charging up the pedal or something like that.

Our trucks have an electric brake booster. The sound is normal as long as it is cycling normally.
Pop the hood and locate the brake master cylinder and booster. Start the truck. The booster pump may cycle on and then stop once it has reached pressure. Have someone cycle the brakes by pressing on and off several times. When you hear the booster pump turn on have them stop cycling the brakes. The booster pump should stop within about 30 seconds. This is all normal and the noise may get slightly louder with age.

Search around for threads about the brake booster when it's not working correctly. It's an expensive replacement.

 

[lugueto]

Thanks for your replies!

Im relieved that its actually normal. Similar to cloudrunner, mine started after maybe 50000miles (80000km). It does work perfectly fine though, didnt know about the electric brake booster, that makes sense.

Appreciate it,

Luis

 

[BlackWorksInc]

Its a normal function, if you have the truck running and you press on the brake pedal about 5 times or so you'll hear it kick in as it regenerates the stored hydraulic pressure in the system.

 

[Bonnell]

I posted this in Yotatech without any response

I have a 2007 V6 4runner Limited 4x4, it started making a noise a while back that has been bugging me. Im suspicious of the ABS system

Everytime you start her up, get her into gear and start moving, about 10 seconds after you get going you get a buzzing sound, very similar to the ABS acting up, which lasts only for a couple of seconds. She doesn't do anything else, no noises, no vibrations, nothing. It only happens after you start her up, you can stop and go all you want and she wont do it again. Everything works perfectly fine: brakes, transmission, everything is in good nick, no weird malfunctions from any system

Any ideas?? Has anybody else experienced this?

Thanks for any help,

Luis

I have a 2008 4runner and my noise starts the minute i put the key into the on position and does not stop even when driving. Am told it would cost $3000.00 Canadain to repair. Brakes work fine so far.

 

[Bonnell]

Its normal, you'll forget about after awhile. I think it is just the brake system charging up the pedal or something like that.


.

Mine never stops making the noise unless in a real deepfreeze. Am told repair would be approx. $3000.00 Canadian . James

 

[earthrealm]

mine only makes the buzzing sound, when ever i step on the brakes, been doing tht for 1,3yrs now

 

[Kmvreter]

Mine never stops making the noise unless in a real deepfreeze. Am told repair would be approx. $3000.00 Canadian . James

When did this start or how long has it been happening? Did you have any brake work done that involved bleeding the system and this happened since then?

 

[earthrealm]

PROBlem is, i dont know when it started, hv had the truck for about, 1.7months now, but recall having the buzzing sound for about 1,3months ago...have serviced the front calipers twice b4 changing them out with napa, serviced the right rear about twice too, so am guessing air has entered the system, or air was in the system prior to purchase........

just living with the buzzing now, i still dont think its normal for the system to be recharging everytime you brake and keep your foot on the brakes

 

[Kmvreter]

Please see my response at Post #12 in this thread: http://www.toyota-4runner.org/4th-gen-t4rs/145716-brake-bleeding-w-abs-w-o-sst-tool.html#post1425485

Here is the brake bleeding pages from the FSM. I had better success relieving the pressure in the accumulator by patiently pumping the brakes every 10 to 15 seconds and holding the pedal down on each cycle with the ignition off. You will notice when all the pressure is relieved and the pedal effort increases. You may have to do this several times to see improvement.

This was specific to the bleeding process but it may help with the (almost) constant accumulator cycle. Who knows, worth a try. May take some time but it's free.

 

[Kmvreter]

[MENTION=108506]Bonnell[/MENTION],
Please see the attached brake master cylinder components diagram.