slopoke

Hey there, just trying to figure out what is going on with my brakes. My light came on yesterday that says brake lining. we i just did all new brakes a month ago as well as sensors. so i am going to work on it tonight and see whats going on. my question before i dive in, is i want to check each sensor, when i touch the contacts should it read 0 ohms? or infinite? Thanks for the heads up!

Raygt3

should read zero

slopoke

ok great thanks. will see whats going on tonight. cant imagine why it lit up with new pads and sensor jsut recently...

tower

Zero ohms on a fresh installed brake system? It should read infinite because making contact on the rotor is what turns on the brake wear light I believe.

Raygt3

On my Porsche wearing through the wire (Sensor) resulting in an open circuit, infinate resistance, and an alarm. Again, new ones should be zero. Disconnect a sensor resulting in infinate resistance and see what happens. Let me save you the trouble you get an alarm.

slopoke

Thank you for all the great feedback, The first one i pulled off was the front left (just where i started) and it seems to have a "break" (infinite) in the circuit when testing between the two poles.... I would imagine that it is the rotor that would wear through the wire and cause this issue, and since these are new with new pads there must be a flaw within this sensor somehow. I left it off and its on my desk until i can go get a new one. and i still have the dash light "brake lining wear" So I figure it must have a complete circuit for no alarm (0 ohm), then breaks the circuit (infinite) to cause the alarm.

Raygt3

Your thinking is correct. The logic is "fail safe", if the sensor should fail, you will get an alarm. It is the rotor that wears through the internal sensor wire giving you an open circuit and the resulting alarm. You could actually test this by attaching and alligator clip or like to the terminals on the car side and the alarm should go away. Or cut the end of the bad sensor off and twist the wires together and replug. Makes a good test fixture for next time. These are just one of those things that are counterintuitive.

slopoke

It just bothers me because these were new one month ago, and (boy did I get lucky starting with the one i did) one of them reads bad already. Oh well, only 3 dollars at least.

Also thats a great tip, I will cut and twist the wires together as a test fixture, that just sounds like fun!!

tower

Interesting. Mine don't work that way. The pads have a small hole that the conductive end of the lead is inserted into it (this is an 02S500 by the way). With new or good brake pad thicknesses, the brake material is the insulation between the wire and the rotor. Once the pad wears sufficiently to expose the lead, it contacts the rotor thereby completing the circuit and turning on the alarm.

You wouldn't by chance have a picture of an old and new pad for a look see?

Tower

slopoke

No sorry I don't. But here is my question. Since it has two leads in it, then it would only make sense that a new one was a "complete" loop. Otherwise there is no point in having two connector pins if it was just sensing for a ground against the rotor? I have yet to have time to mess with it. Was hopin tonight but we will see. Interesting topic though!! Wish someone had a new one in front of them and could post a test of it with a volt meter