1994 E320 station wagon ABS sensors issues - PeachParts Mercedes-Benz Forum

dmorgan · #1 07-03-2012, 04:44 PM

Hi Everyone:

Just had four new brakes pads replaced on the E320 station wagon. The sensor brakelight came on the dashboard just in time before the damage on the rotor could have been worse. I asked the mechanic to check on the ABS sensors on all fours. The mechanic told me that all four ABS
sensors have to be replace. All told in labor and parts costs for the ABS sensors replacement comes around $1,160. I checked the cost of each of the ABS sensors and comes around $170 each. I tried to find some information on how to install these sensors and came up empty. My question is this: Are the ABS sensors are absolutely necessary to have and is it worth replacing them? What about these Brake Pad Electronic Wear Sensor that cost only $3.00 each? Would that be sufficient to replace instead of the more expensive ABS Sensors? I am confused and need guidance and advice on this issue. Thanks for reading.

jcyuhn · #2 07-03-2012, 04:55 PM

Step 1: Acquire new mechanic, yours is either incompetent or dishonest. Neither is acceptable.

First, this car only has 3 ABS sensors. The rear wheels are controlled together via a single sensor mounted at/near the differential.

Second, if there were a problem with the ABS, you would have a red ABS warning light on the dash. So long as that light comes on before you start the car and goes out after, then the ABS system is fine. If the system has a problem reading any one of the three ABS sensors, then the light will be illuminated and the ABS disabled.

daddi · #3 07-03-2012, 05:37 PM

Quote:

Originally Posted by dmorgan

Hi Everyone:

Just had four new brakes pads replaced on the E320 station wagon. The sensor brakelight came on the dashboard just in time before the damage on the rotor could have been worse. I asked the mechanic to check on the ABS sensors on all fours. The mechanic told me that all four ABS
sensors have to be replace. All told in labor and parts costs for the ABS sensors replacement comes around $1,160. I checked the cost of each of the ABS sensors and comes around $170 each. I tried to find some information on how to install these sensors and came up empty. My question is this: Are the ABS sensors are absolutely necessary to have and is it worth replacing them? What about these Brake Pad Electronic Wear Sensor that cost only $3.00 each? Would that be sufficient to replace instead of the more expensive ABS Sensors? I am confused and need guidance and advice on this issue. Thanks for reading.

You're getting royally screwed.

dmorgan · #4 07-03-2012, 06:47 PM

Just pick up my mercedes and the brakes are solid. I should have asked for the olds pads to see if it really is the problem. The ABS sensors light still on the dashboard after driving. I asked the owner about the ABS sensors whether is it really necessary to have those on. His respose was the only thing the ABS sensors does is to let the driver know that brakes pads are getting low in traction with the rotors and beginning to wear out and needs to replace the brake pads. Right now, he said I really don't need the ABS sensors since the brake pads are new and I drive less than 100 miles a month. Any comments?

daddi · #5 07-03-2012, 07:13 PM

ABS Stands for Antilock Brake System. That means that the tires wont lock up under heavy braking, the ABS sensors are three, one on each front wheel and one on the rear diff pinion. If the system is working as it's supposed too the sensors monitor the wheel speed by a method of small electric current produced by a magnetic field from a small magnetized ring the sensor reads from. If the electric current from one wheel gets too low the computer controlling the system reads it as a wheel locking up and activates a high pressure electric motor inside the ABS valve box. The electric motor maintains maximum braking power while electric valves alternate the brake fluid between the locking wheel and a bypass, as soon as the bypass opens the brake fluid pressure to the wheel drops and allows the wheel to turn for a split second, as soon as the bypass closes the wheel brakes again. If your mechanic does not know this than maybe he should not be fixing something composed of more than one object.

daddi · #6 07-03-2012, 07:23 PM

The most common problems with this system is the over voltage protection relay or rust on the front wheel sensors, i've seen one or two failed front wheel speed sensors. Front wheel speed sensors are all the same for the two wheel drive cars made after 1987, as can the plug for the rear sensor fail it's under the rear seat on the right side next to the central locking pump.

dmorgan · #7 07-03-2012, 07:33 PM

Thanks for the information, daddi. What do I need to do? Check the ABS sensors or replace them or leave the ABS sensors alone? Should I take the Mercedes to a Mercedes Dealership to check out the ABS Sensors? Can you recommend an honest mechanic that is knowledgable? The nearest dealership is in Nashville, Tenn.

daddi · #8 07-03-2012, 07:43 PM

ABS is a part of the cars safety, i bet you would not drive around with a broken seatbelt. The problem with going to the dealer is that most of their staff is trained to deal with the newer cars witch have a very different system and don't have a clue how to fix something that they can't plug up to a computer. I'm sure you will find someone that specializes in older Mercedes in the yellow pages or even on google.

daddi · #9 07-03-2012, 07:45 PM

Nashville Mercedes-Benz Repair Shops | Independent Mercedes-Benz Service in Nashville, TN | BenzShops.com

rickjordan · #10 07-04-2012, 10:01 AM

what is your skill set, when it comes to working on cars? The aforementioned abs sensor system is one of the simpilest things on the car. On each wheel, with the wheel removed, you will see a ring that looks like a toothed gear. near it will be the sensor itself, which is nothing more than a electromagnet. As the "teeth" of the sensor ring pass by the sensor (magnet) it creats a electric pulse. If there is too much rust on the teeth of this ring, it could affect the ability of the sensor. So the easiest and free thing you can do is remove the front wheels and wire brush off any rust build up. See if that takes care of the light.

As for your brake pads almost wearing down to the point of scoring your rotors, that meant either your previous set of brake pads did not have the wear sensors in place, or and less likely, the brake wear bulb in your dash is burnt out. The sensors again are really realy simple. Simply put it is nothing more than a that sits in a slot in the pad. When the pad thickness gets down to about 2mm, the wire would then be touching the rotor, completing an electric circuit, which illuminates the brake wear light on your dash.

dmorgan · #11 07-04-2012, 12:19 PM

Thanks for the tips!! I appreciated it. Will check out the ABS sensors to see if there is rust or something that blocking the contact.

dmorgan · #12 07-04-2012, 01:03 PM

Just curious. How long does those ABS sensors supposed to last? Since it is a 1994 E320 station wagon that I bought in 2005, I have no idea if the ABS sensors have been replaced before 2005. Also, in respond to daddi in regards to locations of the nearest mercedes benz specialized repairs, I found one in Clarksville, Tennessee. I checked the Better Business Bureau on the shop's reputation and it shows A+. The name of the shop is
Small Car Enterprises. Any Comments ?

jcyuhn · #13 07-04-2012, 04:19 PM

I think you might be confusing the ABS sensors with the brake pad wear sensors. These are two seperate things, both located in the same general part of the car.

What light do you have on the dashboard? The brake pad wear light is yellow and the ABS light is red.

dmorgan · #14 07-04-2012, 04:48 PM

I just checked the lights and the manual. I apologized for the errors. Yes, it is the yellow light on indicating Brake Pads worn down. It is not the ABS sensor light at all. Again I apologize and like I said I am a newbie in this. What to do with the Brake Pads worn down light on? I already put in new Brake Pads on the Mercedes as indicated above.

Kestas · #15 07-04-2012, 09:53 PM

I'm glad you sorted out the two issues. If the brake pads are new and the brake pad wear warning light is on, then the sensor wiring was probably dressed wrong during installation (either pinched or worn), and is making contact with ground.