brake sensor
 

can a brake sensor go bad??? My brake lining light when on, i checked brakes and my rear were getting low. i changed pads and new sensor. is there a way to test sensor? did i put sensor in wrong? i'd appreciate any help as the lining light is bugging me again. or is my front sensors bad, but the linings look good.

Brake sensors a cheap to buy and I would change the front too just to be safe anyway.

The sensors on my 1991 300CE are pretty simple, they produce a signal when shorted.

Even after you get your warning light , there is plenty of pad life left.

I had a signal from newly installed rotors, pads and sensors. I failed to tuck the excess wire under and it was quickly shorted by the turning wheel.

glenmore
1991 300CE
1990 LS400

As Glenmore notes, all these do is provide a grounding path for the light bulb. When the pad wears to the point that the rotor chafes off the insulation on the wire, the circuit is completed and the bulb lights up. Any point of ground contact will also light it up, so you'll need to check them all to locate the point(s) of contact, assuming the pads aren't yet worn that far..
I've been successful in reusing the front ones by dabbing the wire ends in RTV sealant, to 're-insuate', before inserting into the new pads. :)

They are cheap, and some kits include them anyway, so I don't bother with r&r-ing the old sensors...and yes, from experience, improper install can set off the light easily...

Never mind, found my problem
 

the rear was bad and I did replace, when I still got that lining light I then disassebled the front pads and wala....... :o the front pads were wearing at the sensors too. Funny both wore out at same time. It looked good still visually. Thanks anyways for the help.

Can anyone tell me why my light lites up when I start the car, but now that I'm getting a grinding from my rotor, I still don't have a warning light?

Maybe they didn't put them in?

84 300SD and on Sunday all was good, now here it is the following Saturday and I have front and rear drivers side grinding when I press the pedal.

Maybe you've worn thru the sensor and the pads are almost totally gone?

Pull the wheels off and take a look.

glenmore

1991 300CE
1990 LS400