star5

To our Lexus lovers,

I am driving a 97 LS400 for the last 5 years, has been great.

Recently, my brake light turned on (2nd light from the right on the dashboard, red circle with 4 short curve around it). It is not on all the time, it usually turned on after 3-10 minutes.

So I brought the car to a technician, the conclusion was the master cylinder was bad and rear brake pad needed to be replaced.

Ok I had the brake pad and the master cylinder (without the brake reservoir) replaced.

The technician found there was a lot of mini black rubber when he bled the brake. That tells me the master cylinder should be replaced. However, the light is still on after a while.

Then I think maybe the brake sensor was bad, so I have the master cylinder replaced with another one set (together with brake reservoir), problem remains. Now I am so frustrated. Am I missing anything? Is there a sensor reset? Please please share your experience.

Thanks.

JBrewster

Did you replace the brake sensor that attaches to the brake pads? There's one on the front and rear passenger side.

NJ240sxMan

Also make sure your brake fluid is filled to the proper height.

star5

No, I didn't know there was a sensor for the pad.. I thought the sensor is in the break resevior for fluid level check only. When I replaced the rear brake there was not much left, that could be the issue, but how could I determin whether a sensor needs to be replaced.

The brake fluid has always been fine.

Many thanks.

JBrewster

There is a wire that goes to the top of the inside pad on both the front and rear passenger side brakes. Since the rear pads got so low it's probably the rear that needs replaced. The end that connects to the pad will be worn down; I don't know exactly what it would look like since I replace my pads before the light comes on, so the wear sensor doesn't get worn down.

List price on the sensor is 64.74. If you shop around you can find it cheaper.

cpcc

Its a break sensor issue. You can directly connect the 2 ends of the break wire sensor at the level of the caliper and all will be well.
Attempt at your own risk, as the break sensor should go on when there is little pad left. In your case it is not working anyway.