hey all, been lurking for a while and finally joined up. just traded my 97 SR5 in on an 05 V8 sport ed. vehicle is in great shape (60k). the truck drives like butter but i cant get past how intrusive the buzzing in the brake pedal can be. i'd say 2 out of 3 times i touch the brake pedal, what i assume is the electric brake accumulator "buzzes" into action for about 2 seconds, then clicks off. the service manager took it around the block and told me that was "normal". i've driven other 4th gen runners and i never felt anything like what i'm experiencing here. if i'm in traffic, the pedal is almost constantly buzzing. i don't know if it's a pnumatic system (possible air leak) or what else could cause what seems to be an over-activity of the function. the brakes feel great- it hasn't affected the braking whatsoever. is this in fact normal, or should i take it to another dealer to check it out- the car is covered for another 60k/5 years. thanks folks.

-Ryan

hello? any other v8 owners care to reply?

I have an '03 V8 and I have never heard said "buzz".

It is very common and considered normal but I never noticed it on my 05 V8.

Koz

[QUOTE=Ryco4R;621743]... what else could cause what seems to be an over-activity of the function. the brakes feel great- it hasn't affected the braking whatsoever. is this in fact normal, or should i take it to another dealer to check it out- the car is covered for another 60k/5 years...[QUOTE]

Not sure if it's normal. Mine is reasonably quiet with no feeling of "communication" through the brakes when on the peddle.

Here is the problem symptom table from the service manual. They only mention master cylinder noise.

You could also try the initial part of the brake bleeding procees to test the master cylinder motor activity. You only need to do Step 2 from (a) to (c). Let us know how long the master cylinder motor is running for. During Step 2(c) it should cycle on and off frequently.

If you still have access to other 4th Gens then compare your results to those on another vehicle. Maybe this is the early signs of a master cylinder failing.

Attached Images

	32-02 pstr4000.pdf (20.8 KB, 599 views)
	32-04 f040001.pdf (71.5 KB, 427 views)

Mine does it too. I was told the master cylinder is re-pressurizing the lines. It's normal.

I experienced a similar situation, only more extreme.

My accumulator pump would repeatedly cycle in approx 15 second intervals. It did not matter whether the brake pedal was pressed or not. It was diagnosed as an internal leak. If it becomes severe, the vsc/trac and abs lights will turn on.

I'd start by popping the hood and then put the key into the ON position (the detent before you crank to start it). As the pump pressurizes, see if you can hear the sound of fluid "squishing" or any sort of a leaking sound. This would indicate trouble down the road. This part is not serviceable, but replaceable and quite expensive.

I've put 95k miles on my '03 since new, and it has always done that. More than a few other people have reported the same thing.

I'd ignore it if I were you.

have a similar problem.. a search led me here..........hope you were able to resolve your problem......
......mine only happens when am stationary in drive and am using the brake to hold the car, i feel the slight tremor on my foot, and on quiet nights, i can hear the buzzing..every 8 to 15secs.......see the link below for my thread...and possible solutions i got....btw 4yrs too late!

weird problem .... what could be wrong

Mine buzzes slightly too, but you really have to listen for it... its normal and apparently did it from the time the truck is brand new. dont worry about it.

I just had what I assume is the pump repeatably pumping and with an almost rusted squeak with the pump sound. Then the vsc/trac and abs lights and brake light came on with a constant beep from the dash. I turned the truck off and on a couple times and all the lights and sounds including the pump sound quit.

What was your cost on the repair? and was it the accumulator?

I just had my brake hydro boost unit replaced on my 03 V6 to the tune of $3941.00 was what I was quoted by Metro Toyota in Victoria BC ended up paying 3627.67. I had to wait almost 2.5 weeks for the part since it was back ordered. Mine was diagnosed with a bad ABS pump which unfortunately with anything to do with the brake master assembly requires usually a complete replacement.

yowza!! I hope this is nothing like that. The sound is gone right now and I took it for a quick run to see if would happen again to no avail. Let's hope if it does happen again it won't be leaving me deserted somewhere.

My 2008 was buzzing so loud every 15 seconds anyone riding in the car would immediately comment. I sucked most of the brake fluid from the master cylinder with a syringe and bled the brakes from the right rear and then the right front to remove all the old fluid from the lines and presto! no more buzzing!! I'm so relieved. Good luck y'all

That's good to know. Maybe you got some air in the hydroboost unit somewhere. Yet another reason to change the brake fluid on a regular basis (reducing the risk of stuck calipers and other corrosion in the system are other reasons). I can't imagine why Toyota doesn't recommend it as a regular maintenance item.