What is your question?
About 4 months ago warning lights and code indicated faulty brake booster. Toyota service quoted about $3500 to replace so I let my independent mechanic locate one, which had been pulled from another vehicle, and replace for about $2300. Since then, I've had to return vehicle to him on 2-3 separate occasions due to the brake booster making a chirping or screeching noise. Mechanic said he is 90% certain the reason for the noise was that he didn't do a good bleed on the brake fluid and there was air in the booster or the brake line. He didn't use the scan tool until the 3rd bleed and I'll be picking the vehicle up again today so we'll see if it no longer is making the chirping or occasional screeching sound. At what point do we assume he has a faulty brake booster and request a replacement since we do have about 6 weeks remaining on a 6 month warranty? With the replacement brake booster, I can hear the electric sound of it clicking on and off more than with original.
What makes this problem better or worse?
It's random
How long has your 2004 Toyota 4Runner had this problem?
about 4 months since the brake booster was replaced
There is a simple test that will confirm if noise is coming from the brake booster - however this test needs to be performed by a professional. It involves knowledge of what the reaction will be when vehicle is test driven for a very short distance. Good luck!
This information is relative to the *vacuum actuated* brake booster system .. You didn’t elaborate which system your vehicle is equipped with.
This information is incorrect. The brake booster on the 2004 4Runner is not vacuum actuated. It is an electrical unit powered by an electrical pump. The sound may very well be caused by air in the system. A scan tool is needed to do a proper bleed of the booster assembly. Please remove the popular response if possible due to its in accuracy.