brake pad wear sensor operation

[Decolliber]

Do the sensors operate by having the circuit broken or having one of the wires grounded? Bentley (460-2) says the sensor is activated by grounding. Some Pelican posts on the sensors say they are activated by the circuit being open. Both sound plausible, since the rotor contacting the wire will both open the circuit and ground it. Which is it?

I ask because the brake pad warning light is coming on intermittently, and I plan to disconnect them all and then plug back in one by one to see if one of the sensors is causing the problem. If the sensor is activated by the circuit being broken, then the two wires would need to be bridged at the plugs after disconnecting the sensor. If grounding activates the sensor, then they would not need to be connected. It seems to me that if grounding activates the sensor light, then you should only need one wire, not two.

[cashman]

Not sure the technical answer to your question but if the wires are unplugged the light should come on.

You might want to check your voltage regulator. 16V would cause my seat belt light to.come on.

[darrin]

also seems that once the module containing the seat belt light/brake wear indicator/etc. is damaged by a failing voltage regulator's voltage spikes, it continues to display the same sporadic problems. Even though I'm now monitoring voltage in real time and know spiking isn't occurring, my seat belt light still sporadically illuminates and I occasionally have phantom brake pad warnings -- which clear by "rebooting" the car

My mechanic suggested that replacing the module will solve both of these issues.

[porschenut]

It's based on an open circuit. The light will come on simply by unplugging one of the sensors.