Ls400 Brake Wear Indicators.

[Mile_High_Flyer]

Hi guys. Query. My 1999 LS400 brake pads are getting down a bit, at 95,000 kilometres. If I left them long enough that the wear indicator lights come on, this would theoretically mean the sensor wire should be replaced. Does the wire earth to the disk, thereby lighting the warning, or does it have a loop which wears through so there is an open circuit? If it's open circuit, could one solder a loop of wire onto the worn area, thereby getting it to work again? Likewise, if it earths to the disk, could a similar repair be done? If that wire sensor is totally removed, will the warning light stay on? I keep a pretty close watch on the pads, so lack of a sensor would not be a problem, but it would still be preferable to have them. Cheers, Keith.

[steve2006]

Hi guys. Query. My 1999 LS400 brake pads are getting down a bit, at 95,000 kilometres. If I left them long enough that the wear indicator lights come on, this would theoretically mean the sensor wire should be replaced. Does the wire earth to the disk, thereby lighting the warning, or does it have a loop which wears through so there is an open circuit? If it's open circuit, could one solder a loop of wire onto the worn area, thereby getting it to work again? Likewise, if it earths to the disk, could a similar repair be done? If that wire sensor is totally removed, will the warning light stay on? I keep a pretty close watch on the pads, so lack of a sensor would not be a problem, but it would still be preferable to have them. Cheers, Keith.

[/quote

Hi,

They are on a loop so when the wire breaks the lights comes on, apparently you can repair them but I have never done it personally,the other option is to join the 2 wires together and regularly check your brakes.

[curiousB]

Yes its just a $79 loop of wire and short cable harness.

Open circuit means brake wear sensor has been ruptured/severed.

[AndyLowe]

Yes its just a $79 loop of wire and short cable harness.

Open circuit means brake wear sensor has been ruptured/severed.

The Instrument Cluster Brake Warning Lamp remains off, if it receives a ground signal from one wire, reporting from all four brakes in series. The ground begins its journey and goes to the passenger rear brake sensor. If it makes it through that sensor, it then travels to the driver's rear sensor. If that sensor too is good, it travels to the driver's front sensor, and then onto the passenger front sensor. It leaves this last sensor and then off to the Instrument Cluster.

A broken sensor (0pen circuit) on any one of the brakes, will turn the Brake Warning lamp on as they are all in series. Applying a circuit mod of adding a ground at the passenger front brake sensor wiring, would eliminate brake monitoring and turn off the light. You might have to remove the inner fender to gain access to the wiring and add a good ground.

I have the same problem on my car and bought a subscription to www.alldatadiy.com and studied the wiring diagram. It's on sheet 5 of the "Combination Meter" a fancy term for the Instrument Cluster. I too need to do this mod as my brake pads are thick and I listen for the opposite.

Good luck!

Andy

[1990LS400]

Lexus LS cars don't necessarily have a brake wear sensor at each wheel position. It depends on model year, the market in which a car was sold and maybe even specification/option package. My 00 LS400 has only two brake wear sensors -- only on the right side brakes. My 90 LS400 didn't have brake wear sensors - at least not electronic ones. Some gen 1 LS400 LS400/Celsiors had an electronic brake wear sensor at each brake.

The OP is in New Zealand where LS400's are equipped differently than those sold in the U.S. Maybe his 99 LS has brake sensors on only one side like the U.S. 98-00 LS400 and maybe not. According to the documentation I've seen, LS400's sold in New Zealand had a substantially higher level of standard equipment and numerous features that were not available in the U.S.

[Mile_High_Flyer]

Lexus LS cars don't necessarily have a brake wear sensor at each wheel position. It depends on model year, the market in which a car was sold and maybe even specification/option package. My 00 LS400 has only two brake wear sensors -- only on the right side brakes. My 90 LS400 didn't have brake wear sensors - at least not electronic ones. Some gen 1 LS400 LS400/Celsiors had an electronic brake wear sensor at each brake.

The OP is in New Zealand where LS400's are equipped differently than those sold in the U.S. Maybe his 99 LS has brake sensors on only one side like the U.S. 98-00 LS400 and maybe not. According to the documentation I've seen, LS400's sold in New Zealand had a substantially higher level of standard equipment and numerous features that were not available in the U.S.

Yes, I've noticed some of ours appear to be better equipped, as standard. But mine is actually an import from Singapore. I can't remember which wheels the sensors are on, but I do know there is only one at the front, and one at the rear. Thanks everyone for the information.

Oh, incidentally, to have timing belt, water pump, idlers etc all replaced, is cheaper here in our dollars, than in USA. When currency converted, it's even cheaper, and that is using all OEM gear. But motor mounts are far cheaper to buy in the states, and ship to here, than buying here. Cheers, Keith.