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I replaced the front brake pads on my 04 Mini Cooper S because the check pads light came on and I was able to remove the sensor and install it in the new left side pad but the light remains on. I've been told that once the light is triggered the sensor must be replaced. How does this sensor work and is there any way to test it? And why is the sensor inoperable once the light is triggered?
the sensor is nothing more than a loop of wire encased in the plastic. As the pads wear down, eventually the sensor begins to hit the rotor as well and it also wears down. Eventually the wire contacts the rotor and ALSO wears away until it is broken. The wire is a simple circuit and when the wire breaks and the circuit is OPEN / broken, the light comes on.
So when the sensor 'triggers' it is consumed and must be replaced. (or eliminate the sensor by cutting the end off and soldering the wire ends together ... you'll make the system see a new sensor ... just go back to checking your pad thickness yourself ...)
Note that a new sensor ALSO requires the system to be 'reset' ... just turn the key to position 1 and wait for a few seconds and the light should go out (different then a GEN2 which will clear itself when a new sensor is installed)
If you have a worn/triggered sensor ... look very carefully at the end that was in contact with the rotor face and in the black plastic you'll notice two metal spots ... the remains of where the wire was ...
this is a GEN2 but they are similar ...
the sensor is nothing more than a loop of wire encased in the plastic. As the pads wear down, eventually the sensor begins to hit the rotor as well and it also wears down. Eventually the wire contacts the rotor and ALSO wears away until it is broken. The wire is a simple circuit and when the wire breaks and the circuit is OPEN / broken, the light comes on.
So when the sensor 'triggers' it is consumed and must be replaced. (or eliminate the sensor by cutting the end off and soldering the wire ends together ... you'll make the system see a new sensor ... just go back to checking your pad thickness yourself ...)
Note that a new sensor ALSO requires the system to be 'reset' ... just turn the key to position 1 and wait for a few seconds and the light should go out (different then a GEN2 which will clear itself when a new sensor is installed)
If you have a worn/triggered sensor ... look very carefully at the end that was in contact with the rotor face and in the black plastic you'll notice two metal spots ... the remains of where the wire was ...
this is a GEN2 but they are similar ...
OK, Thanks for that info. So an open circuit triggers the pad light.
Perhaps I could solder a wire between the two spots on the sensor and cover it with some JB Weld plastic bonder epoxy? (This is great stuff, BTW).
Not that I am that cheap (which I am) but I'd hate to tear the fender liner getting at the sensor connector hidden behind it.
