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newyork5star 01-03-2012 01:57 PM

1 Attachment(s)
I want to thank all the people who post here because the info has saved me thousands $$$$!
Hope this post helps someone else.
My CLK320 has had warning light issues (ABS, BAS, ASR, etc) for the last 3 weeks. I came to the forum to look for a solution. Not only did I find comprehensive info, but pictures and diagrams!
I read all the posts and a lot of people seem to have the same problem with warning lights. Everything from checking the battery voltage to checking for codes was suggested. Most of the posts said to replace the stop light switch so that’s what I did.
PROBLEM SOLVED: I solved all of my warning light problems (BAS, ABS,ASR, etc) with the purchase of a new stop light switch.
The switch cost $29 at the MB dealer here on Long Island.
I followed the instructions for replacing the switch that I found here on the forum. With a Phillips screw driver it took me eleven min. to change out the switch. The dealer wanted $240 to do the same job.
After I had the old switch out I was curious as to why MB switches fail so frequently so I took it apart to see what made it work. What a simple concept switch to cause so many warning light problems.
As you can see by the included PDF with multiple pictures I have shown all aspects of the defective switch if you are interested. The burnt contact is what causes our warning light issues. If full FLAT contact is not made in both terminals of the switch the computer is fooled into thinking that the power source is weak or that another component has failed. This is the same design principle as was used in a set of “POINTS” in the distributor in older model cars. Now that cars are electronic ignition these “points” distributors have been eliminated in most cars.
1) Remove (4) screws in the BLACK plastic cover that hides the underside of the dash. Three are all in a row and one is over by the hood/bonnet release and this one is recessed. You will need a Phillips screw driver. Once screws are removed lower the cover and you will see the underside of the dash and brake arm area. You CAN’T remove the panel completely because the hood/bonnet release is attached. Just lower it so you can have work space.
2) With your flashlight, look up under the dash and locate the switch at the top left (US CARS) of the brake pedal arm. Find the clip in the PDF file pictures and squeeze while turning the switch CLOCKWISE to release it from the mount.
3) There are two wiring harnesses to the switch. One small, One Large. BOTH have releases that must be pressed to get harness released. On the small harness I used a very small blade screw driver to pry the harness away from the switch. This small harness has small “plastic cleats”, that hold it in the switch. Take your time and go back and forth from one side to the other until the harness disconnects.
4) On the Large harness squeeze the side releases and wiggle back and forth side to side until it releases.
5) MOST IMPORTANT… Place NEW switch next to OLD switch and make sure white plunger is the same length from mounting base to the tip. If NEW switch plunger is longer take a pair of needle nose pliers, place tip in the squared indentation at the top of the plunger and slide backward toward the switch, it should lock into place at a shorter length. If your old switch is the same length as the new one you don’t have to do anything. I believe that this switch is used in many makes and models so it needs to be different lengths for different cars.
6) REINSTALL THE SWITCH… Push both harnesses into the switch, make sure they seat all the way. The switch can only go in ONE way, it has a small slot and a big slot. Insert the switch into the mounting bracket, turn COUNTER CLOCKWISE. Raise the black panel back into position and install the four screws… YOU ARE DONE! You should have NO BAS, ASR, or ABS lights now.

If you need additional information just email me and I will be glad to help with your stop light switch “Quick Fix”.

iceman350SL 08-29-2012 04:03 AM

thanks. I will try this tomorrow and see how it goes :)

A1EK 08-29-2012 01:19 PM

Glad you got it fixed ! this is a very common fault on W210, W202, W208 cars.....

rsparso 08-29-2012 05:45 PM

Anyone have the part # for the switch ?

iceman350SL 09-07-2012 06:45 AM


Originally Posted by rsparso (Post 5407587)
Anyone have the part # for the switch ?


thats the number on my old switch. Hope it helps.

iceman350SL 09-07-2012 06:47 AM

as promised,

Had the part replaced after the light ( ASR BAS )on the dash kept lighting up all the time. I checked these forums and determined that it was in fact the brake switch. Had it done at my local car guy on wednesday and it worked !!! :bowdown::D

cleharris1 08-03-2015 03:10 PM

I have a 1999 Mercedes CLK 320.

ASR/BAS lights on the dash stays on. Does anyone have any suggestions?

I replaced brake light switch, brake booster, and Brake Module.

Took car to dealer who performed diagnostic test and said the problem is the brake module. I replaced it twice but lights are still on.

I would appreciate your help.


kprent97 12-29-2015 08:38 PM

You sir, saved me hundreds ($$$) last week. My 2000 SLK 230 gave me the same indications. One swift visit to Nextdayauto and I had the switch replaced within 48 hours for less than $25 (w/shipping)! I now know I can contort into a pretzel (mirror free) and complete the job blood-free and most importantly, dealer-free!! Happy New Year my friend!

television 12-30-2015 12:03 AM

What happens with these switches is they can kill the speed signal within the ESP ECU, many assume that because the brake lamps work, it cannot be part of the problem.

Applies to 202,203,208,209,210,211,215,219,220,230

3dogsrock 05-22-2019 01:53 PM

My ABS, ESP and BAS lights have been on since I purchased my CLK 320 Convertible A208 a year ago. I have tried everything mentioned in these forums. So, I purchased a Craftsman 1681 scan tool, it is the same as an Innova 5100. Both of these are compatible with my vehicle and should read the ABS codes. The scanner will read everything else on the vehicle, however, when I ask it to read ABS codes it tells me that I am not connected to the vehicle!. I am connected because I just ran a full diagnostic! Called support and they have no idea except to say that my vehicle is not communicating with the scanner when checking ABS. Any help in this issue would be appreciated.

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