All,

My wife's '00 4runner, 3.4l, 2wd limited (100k miles) has a sudden brake problem I've never seen in any vehicle before.

When going slow, like pulling in or out of a parking spot, there is virtually no brakes. The pedal is extremely hard to press.

However, at higher speeds (anything over 15mph), the brakes still start off very hard for a few seconds, but then the pedal eases up and acts normal and you can slow or stop with no problems. The normal behavior only lasts for the duration of that braking situation. Once you start driving again, it goes back to the hard pedal at first followed shortly by normal brakes.

No idiot lights are present. Brake fluid level is fine. Brakes might have 20-40k miles on them. This problem happened all of the sudden. The only other thing to add is the truck now starts really slow, almost like the battery is weak. I doubt the starting issue is associated with the brakes but I'm just throwing out there in case.

So any thoughts? I'll flush the lines with new fluid. I'm thinking the brake booster is the most likely culprit but I've actually never heard of one going bad (any tech write-ups on replacing?).

Thanks for reading. I'd appreciate any info,ideas or comments.

Regards, from, Arizona,
Lars

 

Ya know.. I've never heard of a brake booster going bad either.
It could however have a vacuum leak in any of its vacuum lines..

I'd flush the brakes then check for vacuum leaks.