W140 Brake Sensor
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Joined: Jul 2006
Posts: 35
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From: Houston, TX.
1994 S320 (W140)
W140 Brake Sensor
When I first bought my car in June 06 I had to change out the front brakes because they were worn out. Just this weekend my brake light came on and I figured it was my rear brakes so I changed them. The brake sensor light was still on so I checked the front brakes and they were about half way down but still good for a month or so. So I told the mechanic he had put the rear brakes on wrong and he said that the rear brakes dont have sensors!
Tell me is this bs or what, somebody tell me if this guy just did a half *** job and didnt want to get to doing it right. So he says that it is the front brake sensors that go off when the brakes are half way down.
Well if anyone has had this problem before I would appreciate it if that person can give me some insight to what I need to do because I do not want to repay this guy to fix it I would rather just make the alterations my self. Do you think I need new sensors or that the guy just didnt install the brakes right. Your response would be greatly appretiated!
Aaron
Tell me is this bs or what, somebody tell me if this guy just did a half *** job and didnt want to get to doing it right. So he says that it is the front brake sensors that go off when the brakes are half way down.
Well if anyone has had this problem before I would appreciate it if that person can give me some insight to what I need to do because I do not want to repay this guy to fix it I would rather just make the alterations my self. Do you think I need new sensors or that the guy just didnt install the brakes right. Your response would be greatly appretiated!
Aaron
Senior Member
Joined: Jul 2003
Posts: 455
Likes: 1
From: Fl
92 500sel/01 320e wag
There are holes in the brake pads that the brake sensor plugs into, as the pad wears the sensor contacts the metal rotor and causes the lamp to illuminate. You should notice the lamp coming on when your foot is in the brake. There are four on the front and four on the back (140 body), per the manual, and they should be replaced when the pads are. Also use MB anti squeek paste on the pads backing! The sensors are about $ 1.50 ea, see attached article on how to do the fronts, mechanics cut costs by not installing them!
http://v12uberalles.com/Front_Brakes.htm
http://v12uberalles.com/Front_Brakes.htm
Last edited by Peter Guenther; Jun 20, 2007 at 08:01 AM.
Junior Member
Joined: Sep 2005
Posts: 63
Likes: 1
From: Chicago, IL
1995 S600 Sedan
People often try to use the old sensors over again, because they usually look pretty good still. That shouldn't be done, as pulling on them to get them out can often damage them.
"Vehicles with ETS, ESP or ASR have wear sensors for the brake pad wear indicator on the rear axle.
There are the following versions:
No sensor
2 sensors
4 sensors
There are the following versions on the front axle:
2 sensors
4 sensors.
When replacing brake pads only install as many sensors as were fitted originally. if only one wear sensor is fitted to a wheel, it is to be fitted to the outer brake pad.
Wear sensors which are not connected result in the brake pad wear malfunction indicator lamp coming on due to moisture.
NOTE
The wear sensor cable must be routed as shown in the illustration.
Only the transparent (temperature-resistant) version of the wear sensors may be installed on the rear axle."
"Vehicles with ETS, ESP or ASR have wear sensors for the brake pad wear indicator on the rear axle.
There are the following versions:
No sensor
2 sensors
4 sensors
There are the following versions on the front axle:
2 sensors
4 sensors.
When replacing brake pads only install as many sensors as were fitted originally. if only one wear sensor is fitted to a wheel, it is to be fitted to the outer brake pad.
Wear sensors which are not connected result in the brake pad wear malfunction indicator lamp coming on due to moisture.
NOTE
The wear sensor cable must be routed as shown in the illustration.
Only the transparent (temperature-resistant) version of the wear sensors may be installed on the rear axle."
