I have a 2001 SR5 4Runner 4WD (about 30,000 miles).
There is a strange noise from under the hood that occurs on braking, every 3rd or 4th time I brake (normal gentle braking not slamming the brakes on). So I hear it every 60 - 90 seconds. The noise is like 2 - 5 seconds of a low buzzing (like the electrical sound a refrigorator makes when the cooling components cut in) and then at then end there is a single metallic popping sound. It is a clearly audible sound to anyone in the car.
There is no light on the dash when it happens and there is no noticeable difference (pressure or pumping) on the brake pedal.
The guy at the dealership said it was a normal sound, but my buddy with a 2000 SR5 says he almost never hears it on his truck. So I am assuming that this is a standard noise, but that something inthe braking system is dying out, hence the fact it happens so often.
I am guessing that the ABS pump maybe dying out. Anyone had this happen to them or got any ideas?
Cheers