owali

Pretty scary... driving along the other night and my dash lights up like a Christmas tree. A minute later my brakes are 95% useless. Luckily I made it to the side of the road without hitting anything. I need some help determining what the cause is though. I have been reading other peeps stories on the forum and at first it sounded like a brake master cylinder/booster failure, but I need to make sure before I drop all that cash on a new part.

Symptoms: Strange continuous buzzing alarm from dash, Brake light, ABS and VSC lights on. Almost no braking power left. Pedal is stiff as a rock. It is mostly pressed down and wont budge. When I start the car with the pedal pressed the pedal does not sink. I have not seen any brake fluid leaking, still looks full.

After reading here, I was almost positive it was the BMC/booster. But my mechanic said it was an electrical problem. He said the brakes were electronically assisted and they were not getting power. He said the BMC looked fine. He said I would need to go to Lexus Dealer to get fixed. Now I am really confused

Lexus dealer is 3 hours away so I cant just stop by for a diagnosis. I am wondering if the BMC is fine but the attached booster is bad, but I don't want to pay for a new one on a hunch.

Any help would be greatly appreciated

runyun

iTrader: (11)

Ton's of threads here about it. It's common on the 98-00 year models.
Best bet would to find one used

Exact same symptoms:
Buzzing sound (intermittant) typically last about 6-8 seconds
Then, one day no power assist in braking. Your brake pedal barely moves and the car doesn't stop anywhere close where it needs to. (I almost wrecked on my previous GS because of it)

owali

Just had my master cylinder replaced. Unfortunately, it did not fix the problem. Still no power assist and the buzzer is still going off with the lights. Any ideas?

owali

To add a few more details... the brake pedal is no longer stiff. After having the BMS installed, the pedal can be pushed down, and almost feels normal. However, I still dont have any braking power and the buzzer/lights are still going off.

I think my booster is working now because the pedal sinks if I pump and hold while starting the car.

Does anybody know what the problem could be? Thanks

starfyrels

iTrader: (2)

check your ecu - maybe your abs ecu has gone bad?

also did you have your tech clear the lights?

owali

No, he did not clear the light. I figured once the problem was fixed the lights would go out. Do I need to clear them?

Where is my ABS ecu? could the problem be a blown ABS fuse or solenoid?

99 GS3

iTrader: (14)

It's under the dash below the steering column.

It looks like this:

owali

Thanks for the pic, is there anyway for me to test the unit to see if it is defective?

1sWt2GS

iTrader: (6)

cant help you, but that is sure scary

jryan29

This happened to me two times. I took it to my mechanic who used to be a senior mechanic for Lexus but now has huis own shop. He knew immediately when I called him what the problem was. He has seen it many times. The electric pump motor on the master cylinder failed. The entire master cylinder does not have to be replaced. Only the pump motor. Unfortunately the part is not sold seperately. Lexus will sell the master cylinder for around $2500. My mechanic removed the motor and sent it to a shop to have it rebuilt. This cost me $400. He tells me that there are only like three places in the in tire country that will rebuild them. He said replacing the motor only takes 20 mins. My first motor failed after several months. It is back at his shop awaiting the rebuild once again. Covered under warranty so, no out of pocket.

KYLex42701

I have a 99 gs300 that has the same problem..my mechanic says its the abs system that has gone out. Does anyone know where i can buy an aftermarket or used one?

kdick91

I really think you should report this, since it is a common issue.

https://www-odi.nhtsa.dot.gov/Vehicl...nt/index.xhtml