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Old 02-19-2010, 02:52 AM   #1
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Brake wear indicator - How do they work ?

Hi All

My brake wear indicator light has come on after replacing front engine mount on car, all pads look fine and i think one is faulty.

I am getting conflicting info on how they work....

a) Some say there are two parallel wires that are shorted via the rotor and give fault.

b)There is one wire that is earthed to the rotor thus giving fault.

c) There is a 'loop' of wire that is cut by rotor given open circuit fault.

Which is it so i can quickly find which one/s are giving me this indication.

Cheers

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Old 02-19-2010, 04:23 AM   #2
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The brake wear indicator light comes on when the wire of the sensor breaks. If your light is on, you need to replace the sensor - fairly cheap to do.

Many owners simply cable tie these out of the way, disabling their function as brake pad wear indicators and preventing the light from activating.

Cheers!
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Old 02-19-2010, 05:01 AM   #3
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So unpugging them would still give a fault. I need to check continuity on them to see which one is open circuit ?

Also if i wanted to remove them i would need to short them out ??

Ta
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Old 02-19-2010, 06:46 AM   #4
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Quote:
Originally Posted by bilabonic
So unpugging them would still give a fault. I need to check continuity on them to see which one is open circuit ?

Also if i wanted to remove them i would need to short them out ??

Ta
According to the Mitchell-1 OnDemand system at my library, the wiring diagram (for MY07) shows all the pad sensors wired like the old Christmas tree lights (all in series with eachother) and feeding into the instrument cluster module. Like Lil B mentioned, most people unplug them, short out the connector ends, and cable tie them out of the way.

Regards,
paul...
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Old 02-24-2010, 05:49 AM   #5
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Just whipped wheels off to check all sensors/pads and all looks fine.

I disconnected the plug going to the sensors on each wheel and metered them and they are all short circuit/zero resistance as expected.

Is there another point i can check on the car after they have all been series together ?

I also noticed another plug directly next to the brake sensor plug, it looks as if it's going into the hub, what is this for ??

Totally lost now peeps ??

Cheers
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Old 02-24-2010, 08:31 AM   #6
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The other plug and item going into the hub is the ABS speed sensor. The plugs are different, so no real worries about them being in the wrong spots.

I've heard there is a way you can test the brake wear system by pulling the gauge cluster and testing resistance between certain pin-outs. Maybe someone has their book handy and can give a little better understanding. My brake wear light is on as well, 4 new wear sensors installed. So this'll be something I'll have to do as well.
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Old 02-26-2010, 11:27 AM   #7
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When I bought my Box I knew it had been tagged in the RF fender area. If you pull the fender liner down, you can see evidence of repair work. Done well, but you can tell if you really look.

Today I decided to really look into why my brake light wear was on all the time. Turns out the harnes on that RF wheel was bad also recently causing the ABS light to come on as well. The accident must have tugged just enough on the wires/plug that bolts onto the hub that over the years, a couple of the wires finally worked appart.

Harness from wrecking yard fixed both issues.

Cool!

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