Disc brake pad warning on dash

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Feb 28, 2015 | 06:37 PM

Bewy

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2000 model C240

Disc brake pad warning on dash

I have a 2000 model W203, C 240. The above message came up while driving, which surprised me because all the pads are relatively new, about 6000km on them. I found the sensor wire on the right front pad had been in contact with the rotor & worn through the insulation, bringing up the error. I have repaired/insulated the wire & the error message no longer comes on while driving. However, it comes up with 'malfunction!' when I switch off the ign. I guess there is a reset procedure, not sure. Anybody know what to do?
Thanks.

Mar 1, 2015 | 03:27 AM

Bewy

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2000 model C240

Brake pad warning light

This warning appeared on the dash, 2000 model W203. I found the sensor wire had rubbed through on the rotor on the right front wheel. Pads have 9-10mm of lining remaining. I repaired & insulated the wire but cannot get rid of the warning message in the display. I have tried pushing the reset button for 5 secs, but message reappears. Any ideas? Thanks.

Mar 1, 2015 | 03:28 AM

samaritrey

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From: VA

THE C350

Well if the sensor was worn did you replace it?

Mar 1, 2015 | 04:08 AM

Bewy

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2000 model C240

Didn't you see where I said the pads are relatively new? They are not worn, have about 9-10mm of lining material on them. After disconnecting the sensor from the harness, I checked the sensor leads with an ohmmeter & it read infinity. Once the pads wear to the point that the pads are too thin, I assume the leads are connected together by contact with the rotor & this would indicate low resistance on the meter, not high resistance that I got.

Mar 1, 2015 | 07:51 AM

phister

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Joined: Feb 2009

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From: fort worth, tx

06 C230 SS 6spd

Did you just repair the wire or replace the senor completely with a new one. If you just repaired and insulated as you put it that won't work. You'll have to get a brand new senor to replace it and it should automatically go away. Also is it wire on the sensor or to the harness that the sensor connects to that got rubbed on. Pics would help. Usually replacing the sensor should make the brake pad light go away.

Mar 1, 2015 | 04:00 PM

KSKarl

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Joined: Aug 2014

Posts: 131

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From: Wichita, KS

2002 C230 Coupe

New to MB, but on my previous BMW the computer needed continuity thru brake pad wear sensor. Either short (to ground thru the rotor) or open would trigger a warning.
Perhaps the wisdom of the board can explain better.

Mar 1, 2015 | 04:10 PM

Bewy

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2000 model C240

Thanks for the reply. I am assuming the sensor works like this: the two sensor wires are embedded in the pad material & when the pad wears down, the end of the wires are exposed & a connection made between them [ short circuit ] by coming in contact with the rotor. With the sensor disconnected, I measured an open cct between the wires; it was the thin sensor wire that had rubbed on the rotor & made contact; wire was not broken. I just put a sleeve over the wire & moved it safely away from the rotor. But cannot get rid of the warning message.