entra80

Hi my wife lexus rx350 2010 the brake pedal go to ground when in stop in traffic. and the car start moving after i stop ?? any help
one mechanic told me its braking fluid but im not convinced i hope i get some help

RX in NC

Have you bothered to check the brake fluid level in the reservoir? That is indeed your first step.

entra80

Yes its full.

Clutchless

Does the brake pedal come back up if it is pumped?
If you have not lost any brake fluid the problem is caused by either old brake fluid that needs to be bled and replaced, (when was the brake fluid last replaced, it does age) or and more likely, a
failure of one of the braking components such as the master cylinder, vacuum assist, ABS unit or electronic brake force distribution device. The master cylinder is the least expensive of these to replace. A good repair shop can diagnose and repair this problem. The same basic brake system is used on millions of Toyota and Lexus vehicles.

mdbrown

There are multiple issues that could cause what you are experiencing. I'm going to assume you haven't had to add any fluid so I would say the master cylinder has internal seal failure. I've seen instances where ABS pumps can cause the same issue but since you have no warning lights I don't think that's a possibility here.

entra80

thanks again today i changed brake pad and cleaned brake rotor. the mechanic told me the oil was not coming to brake roter on of them but after i drived the car its better 20%

so i still think should i change the master cylinder. because the lexus service centre will change everything and let me pay 2500 dollar or 3000

Clutchless

Was this an independent mechanic you keep referring too? It sounds to me that you should first have him bleed your brakes as you may have air in the sytem.

$2500 to $3000 is an outrageous price to replace the master cylinder. That is more like the price for the electronic brake force distribution.