1997 E420 brake linings
 

Change the rear brake pads and the idiot light won't stay out. I put on a new sensor and pads with Mercedes brake lining grease. My car won't stop squealing and the idiot light keeps coming back on. I know this is not rocket science but could someone make some suggestions?

Someone told me the lining my have to "wear" in and that is why they squeal. If so what about the idiot light??

Thanks in advance.

By the way, the new sensor is fitted to the outside brake pad.

Have checked the specs on the rear pads and the measured about 4mm. The wear sensor was supposed to come on at 3mm but I changed the rear brake pads anyhow.

I did check the front pads and seem to have about 9mm (without backing plate) left also checked the sensor to make sure I had a tight fit in case it was a moisture issue.

It all seems fine.

Norm, please explain "brake lining grease". Anti-squeal paste is normally applied to the back of a brake pad to prevent squealing when the brake caliper piston(s) vibrate against the brake pad. I get the impression that you applied the brake lining grease to the wear surface of the brake pads. That would be a no-no.

Applied "squeal paste" to the back of the pad. I realize that you cannot put it on the surface of pad.

Did you replace the rotors?

As for the lamp, how are the front sensors?

Rotor did not have to be replaced due to the specs.

What about the idiot light???

I think I would unplug the rear sensor to see if the warning goes off. If so you are getting current flow through the pad. Did you use a new sensor? As to the squealing, it could just be the type pad you used. Did you use the Mercedes pad? I have heard that some ceramic pads will squeal on old rotors, but I have no first hand experience.

I did use porterfield pads and I did use a new sensor. It does turn of the warning light when I unplug the sensor.

It sounds to me like the end that you stick into the pad is no longer insulated and is making electrical contact with semi-metallic pad and thereby to the disk. The sensor system sees the current and thinks the disk is contacting the sensor. It looked to me like my sensors had insulation around the part that goes into the pad, as well as what looked like hot melt adhesive on the end. Maybe your sensor was somehow defective. Since they are cheap, I believe I would try another. When you pull the sensor out you may leave junk in the hole in the pad and may need to drill it out so the new one can go in undamaged.

I bought my car from my neighbor. I listened to the rear brakes squeal every morning as she backed down the hill. When I bought it, I changed the rear pads to the Mercedes pad and they have not squealed since.

I swapped the bulbs in each stop light. One works. Some say the license plate light can trigger the rest of the brake lights to blow. I replaced the license plate light and still nothing, but the left brake light comes on.

Yup, you are the winner. Absolutly right, the sensor was somehow defective.

Thanks you all for all the great support on this forum.