Brake Warning Light

[lovlex]

i replaced brakes in the 93 ls 400 becuse the brake warning light came on. now that i have done that, the light is still on. how do you get this light to go out?????????

thanks!!!!!!!!!!!

[wandawoods]

it could be the pad-wear sensor is improperly installed or broken when your brake job was done. have your mechanic double check it.

last year, midas did some brake works on a 94 LS that I used to own, and they broke one of the sensor wire, the result was brake-pad worn light stayed on. the sensor wire is about $90 and it's sold only at dealer.

[VBdenny]

As far as I know, only two things will illuminate the "BRAKE" warning light.

1. Parking brake is slightly engaged. Happens all the time.

2. Low pressure in either the front or rear system. This means that one of the systems is not reaching the pressure due to a leak. This you can see unless it is a master cylinder failure. To make sure. Start the car and hold your foot with firm pressure on the brake pedal. If it slowly sinks to the floor and then you can pump it back up, the master cylinder is failing. They are easy and fairly cheap to replace but you must follow specific procedures or it will never work properly.

Brake pads have NOTHING to do with a "BRAKE" light coming on unless it's something very new that I haven't heard of yet.

Check to make sure the parking brake is fully retracted. My wife told me once that the brake light was on, after she released the parking brake again (it was hanging on the first click) it went off. Otherwise, crawl under the car and inspect each wheel for evidence of fluid leaks.

Good luck

Denny

[CUMan]

I agree with Denny about the parking brake.

My 1993 LS 400 has this problem all the time. Apparently the spring that is supposed to pull up the parking brake pedal weakens over time. It still pulls up the pedal, but it doesn't move it far enough to turn off the warning light. This is especially noticeable in the winter months.

I have gotten into the habit of sticking my left foot behind the pedal and pulling it forward. This is a low tech answer, but it works.

[1UZ-FE]

VB,

Lovlex is talking about the brake pad wear warning light. Either the 1990 models dont have this feature (my 94 has it) OR u haven't owned ur car for long enough and driven far enough for the brake pads to get thin enough for the light to come on. Look in your owners manual (if u have one) in the first few pages of the book and it shows diagrams of the guage cluster with every warning light illuminated. The light is at the bottom of the cluster and looks like a circle with 2 semi cirlces on the left and right side of the cirlce. The parking brake light inside the tachometer is totally not related.

[VBdenny]

Thanks 1UZ,

That is something I didn't know. I have read my whole owners manual but I don't recall seeing anything on brake wear indicators other than the tiny clips on the pads themselves. I read quickly though and sometimes miss things, so I'll check again. On your car Is there a different indicator light for brakes and brake wear? If not, maybe Lexus should have put a "report to dealer" light in instead. Ha!

I think a wear indicator is a great idea, but if you merge it with the regular brake warning system you take the risk of people ignoring it. Suppose your pads were low and the light was illuminated, then the system develps a leak taking out your front of back brake system? Crash! or you leave the parking brake on, and don't notice because "that light is always on." Then your sense of smell must compensate.

I'd bet a dollar to a dime that the parking brake is slightly hung up. Like CUman, I always use my left hook foot to pull back the pedal or sometimes the light comes on.

Denny

[wandawoods]

indeed on the 94, 'brake system warning light' and 'brake pad wear limit warning light' are at separate locations.

perhaps, lovlex should make clear about which warning light was referred?

yes, there is a sensor wire physically attached to one of the brake component. according to my mechanic, it is very easy to break it if not careful, the result will be a constant-on pad-wear warning light.

[VBdenny]

Good call Wanda. Perfect assessment. I know my 90 doesn't have any wires attached, but it seems like a good idea. What, with windows closed and AC on, you would never hear the inicators on the pads. I am glad they are on seperate light indicators, only mkaes sense.

Denny

[wucantstop]

I had this same problem. My brake pads wore out and when I had them replaced, the light stayed on. I called the dealer to ask about it and they told me that once the pads wear out, the sensor wire breaks and must be replaced (at $90 each x 4). If this is not true, or there is any way to get the light off, please let me know. Also, does anyone know where I can find a picture or diagram of the actual sensor and/or where it's located?

[blake918]

Do these brake wear lights actually work? My rear brakes squeal when I hit the brakes--it's time for some new ones, but I have no wear indicatior lit up on the dash. Anyone have any specifics as to when the light is supposed to come on??

[lovlex]

i am spealking of the brake pad indicator light. it does work as the the car need new front brakes. thanks for all the replies.

[wandawoods]

so, did u get the lite issue resolved? what was the cause in ur case to keep it lited constantly after brake works was done?

[silvermate]

first things first, make sure you have plenty of brake fluid in the resevoir, the little sensor in there is very very sensitive, even if the fluid is a quarter of an inch below the line the brake light will come on

i had the light come on last year, checked my fluid and it was barely below the line..........filled it up...problem solved.

hopefully it will be something as simple as that. :)

[wucantstop]

So was the dealer for real when they said that the sensors need to be replaced each time the pads wear out?

[wucantstop]

And can I somehow bypass the wire sensors to turn the dash light off?

[wandawoods]

So was the dealer for real when they said that the sensors need to be replaced each time the pads wear out?

that's not true! it's just that you need to be extra careful when remove and re-attach the sensor wire. it's very easy to get damaged according to my mech.

[mbpgawest]

Here is what I know of the "brake pad wear limit warning light." If you let your brake pads where down to low, the sensor will make contact with the rotor and turn the light on. At a cost of $90 each, it's best to change your brake pads before they get worn down to close to the sensor.

[ChrisD1]

So was the dealer for real when they said that the sensors need to be replaced each time the pads wear out?

I think they only need to be replaced if broken or like mbpgawest says, when contact is made and the light comes on. I am pretty sure that there will be ample warning (squealing) before the sensor will make contact and the warning light will come on.

I have a broken sensor that I think resulted from the wrong pads being used. The sensor contact seemed like it was heat damaged and crumbled when changing the pads.

My 97 has two sensors not four -- one on the front right and one on the rear right. The other sensor disconnected and reconnected easily during the pad change.

I don't think they are supposed to be replaced each time you change pads unless you waited too long.

[1UZ-FE]

ChrisD1,

Are you saying that originally, your car had 4 brake sensors fully operational and that you disabled both of the sensors on the left side of the car so that only 2 sensors on the right are operational? If thats the case, i guess it's got it's positives and negatives. A postive is that should you wear your brakes down to the point that they contacted the rotor or broke on the side of the car with working sensors, you could then enable the sensors on the left side of the car so that you still had sensors. A negative is that if you should have a sticky caliper (a caliper that does not release all the way and maintains contact with the rotor) on one of the wheels without the sensor enabled, and the pad gets worn down to the point that it starts to scratch/groove the rotor, you wouldn't know if this happened because the sensor isn't hooked up.

Also, i think that i've read somewhere in the LS forum on this site that the sensor is a small piece of wire or something and if it is damaged, you can use a piece of wire or something and it will work the same as the sensor. I've never seen this sensor and have no idea what it looks like. If this isn't true, is there someway else that the real sensor that is damaged can be substituted out with another piece of hardware that can be obtained at places other than the dealer?

[wucantstop]

That's a good question...

[y2k1234]

My 1992 LS400 brake warning light is on and off. Special when I drive in low speed light is on more often. Any one have clue about that?

Thanks

[92Lex]

My 1992 LS400 brake warning light is on and off. Special when I drive in low speed light is on more often. Any one have clue about that?

Thanks

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Low brake fluid.

[glenmore]

Just an aside on the brake wear indicators on my 1991 Mercedes 300CE. This system is simple, cheap and foolproof. The sensors are only a couple dollars each and should be replaced whenever pads are changed. When the wear on the pads reaches the sensors, there is a simple short and the warning light goes on. You have plenty of time to arrange to have your brakes done.

glenmore

1990 LS400

1991 300CE

[pgupta]

Thought I'd clarify. Picture is worth a thousand words - however in lieu of one, here are a thousand words!

The brake pad = 10mm thick braking material on a metal base about 3 mm thick.

One end of the metal base has a rectangular slot into which the wear sensor slips in and is locked in place by a spring clip.

The top face of the wear sensor is 2mm above the metal base. So, once your pad lining wears by 8 mm, the pad surface and the wear sensor top face are on the same level, both touching the rotor. As the rotor continues to grind away, now both, eventually the wear sensor "opens" electrically and the dash light () comes on. This is different from the "BRAKE" light which is driven by brake fluid level.

Keep track of your mileage after new brake pads - typically 6K miles wears out 1mm of pad. So after 36K miles or so, you should think of changing the brake pad. Again, not all wheels wear out evenly. This is just a guide line. If you replace the pads at 4mm to 3mm remaining, you will never have to replace the wear sensor as it would never touch the rotor and get shaved off.

Once the wear sensor has been shaved by the rotor, its too late. The sensor itself costs $40 at the dealer + about $30 labor to install it.

Depending on the model, not every wheel has this sensor. On a 96 Lexus, I have seen it on passenger rear but not on the driver side rear. Haven't looked at the front axle yet.

You can install new brake pads and not replace the wear sensor and ignore the () light. You can't get rid of the light without changing the sensor.

What I don't know is whether you can just strip the wires going to the wear sensor and twist them short to defeat the () light.

So was the dealer for real when they said that the sensors need to be replaced each time the pads wear out?

I think they only need to be replaced if broken or like mbpgawest says, when contact is made and the light comes on. I am pretty sure that there will be ample warning (squealing) before the sensor will make contact and the warning light will come on.

I have a broken sensor that I think resulted from the wrong pads being used. The sensor contact seemed like it was heat damaged and crumbled when changing the pads.

My 97 has two sensors not four -- one on the front right and one on the rear right. The other sensor disconnected and reconnected easily during the pad change.

I don't think they are supposed to be replaced each time you change pads unless you waited too long.

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[92Lex]

What brake sensor? It's a 92 LS4.