Brake wires..?
 

I have a 1980 240D w123, and I drove her home from the guy I bought her off of, and the front brakes are very grabby, but they pulsate. I checked the brakes and found that there is a wire going into the brakes. Interested, I followed the wire up through the wheel well (on the drivers side tire) and found the poor thing cut, tangled underneath a big bunch of wires coming out of the firewall. The rest of this cable goes under the relay box on the top of the drivers side tire well, I found that it has 3 wires wrapped in a black sheath on the cut side of the connector, and 2 wires on the side that goes under the fuse box. So anyway I guess it got pinched or ripped sometime before I got her. Anyone know what these wires are for?? Thanks in advance,
Nick

Brake pad wear sensor?

they alert you to pad thickness by grounding to the rotor when you wear out your pads.
a yellow light on your dash will come on.

I agree.

EDIT: vstech gave the correct technical answer. :D

oh, and if your brakes are pulsating, first check under your hood for abs system, it will be a box with brake lines coming to it from the master cylinder...
if you do not have it, (very rare to have it...) your rotors are warped and should be replaced.

hey thanks everyone, it's the wear sensor. im getting the yellow light on the dash. i'll have to check for that box, i doubt it has ABS but maybe.. the car sat for about a year before i bought it so it's most likely the brakes (drum) being warped. it seemed the harder i pushed the brakes when i could on the drive home the lighter the pulsating got.

Just rust buildup on the rotors from sitting perhaps. Remove a wheel and have a look. Where the pads sat should have no rust in comparison to the rest of the braking area of the rotor. Rotors may clean down enough to be serviceable. If not they can be had for 20.00 or so new apiece. Car may have sat more than a year or in very poor storage conditions.

there is no drum brakes associated with your brake pedal.
there is a drum inside the rotor that is applied with the Emergency/parking brake.
4 wheel discs baby!

ABS on a 240D, that would be nice, was there such a thing? I had 240D with SLS, some folks never herd of that :D

haha i wish i had ABS tood :( but the good news would be it is four wheel disks :cool: a friend said they were drums. and man, she needs a good hour drive with my pinky toe on the brakes the whole time. it had sat for a good year, outside, before i bought it. poor thing has cancer all over the body, but boy the interior is so nice :). so this brake pad wear sensor, it can't short to turn the light on, my light is on all the time now and the wire to the sensor got sliced :confused: im going to fix the wire up this weekend and see how that sensor works. thanks again guys.

Is it really necessary to replace these every pad change if you change the pads before it comes in contact with the disc ? - Thanks

Absolutely not.