doctorc

The ASR/ABs light on my 1994 S600 came on this weekend while I was driving.

The car runs fine and does not go into limp home mode.

The only thing that I notice that is different when the ASR/ABS light comes on is the that steering becomes heavier.

The ASR/ABS light goes off when the car is shut down and restarted and comes back on usually after about ten minutes of driving.

The steering returns to normal when the car is restarted and becomes heavier once the ASR/ABS light comes back on.

I do have brake lights when the brake pedal is pushed.

I have read about replacing the brake light switch.

Any suggestions?

Jackwf

May i know did you feel any pedal pulsation when operate the brakes heavily in light comes on condition?

doctorc

I did not feel any pedal pulsation but the brake pedal seemed to go further to the floor than usual.

The brake pads were replaced about 16,000 miles ago.

Also, I checked the four fuses under the hood where the computer bank is located and they were all okay.

Thanks

BENZBOSS

I have read about replacing the brake light switch...................

Television

The brake light switch does not apply to non BAS equipped cars, and cars without a CAN bus.

The biggest cause is the OVP relay, but this puts the lamp on from cold start. This could just be a wheel sensor thats dirty

doctorc

Thanks!

doctorc

I went ahead and changed the brake light switch, the battery, and cleaned the wheel sensors using brake parts cleaner. Do I need to remove the wheel sensor from the wheel assembly to properly clean it? The ASR/ABS light is still coming on but takes longer to come on. When I replaced the brake switch yesterday, my SRS light, which for the last few months has been coming on and staying on for a couple of minutes at startup, went off as it is supposed to but then came back on again and stayed on as it has done lately. I don't know if any of this is related or not. My next step is to remove and clean the wheel sensors. The wiring harness has been previously replaced.

Any other suggestions?

Runninrebel211

After you do all that besure to reset everything by unplugging your battery for 30 mins. Before you do so make sure you have your factory radio code handy or you will be out of a radio. Sometimes the cars computer has to "forget" problems it thinks it has , that's why you have to unplug it.

syljua

This is the W140 board. W140 does have CAN (industry first!),
but not a separate OVP relay. BAS or not has nothing to do with
the matter.

br,
syljua

doctorc

Syljua:

You wrote that the problem with the ASR/ABS light is the W140 board.

Mine does have the Can as you said.

Is my problem the ASR module in the Can?

Thanks!

syljua

I meant board, as another name of a forum.
I quoted Television since he does not have a W140
and perhaps confuses the parts of the W140 with
other types (W124, W210, etc.)

br,
syljua

doctorc

Thanks for the clarification.

doctorc

I changed the brake light swith for the second time and cleaned the wheel senosors again and reset the computer as directed.

I drove the car for 1 1/2 hours yesterday without using the cruise control and the ASR/ABS lights did not come on.

I drove the car this evening for about 30 minutes. The ASR/ABS lights came on about 5 minutes after I turned the cruise control on.

Any suggestions?

Haroundb

I have exactly the same problem, so if anyone knwo how to fix his it will be possible to fix mine too.

I appreciate your great help people.

Haroundb

Hi, no news.???

merc600

Please see my thread on the same subject. I use my car infrequently - often not driving it for 2 weeks or more. The first trip of the day the ASR light comes on and the car goes into limp mode. A restart will fix it but this can recurr, maybe 10-15 times in only 30km. However, the next trip when the engine is still warm, it is foine. Yesterday I did a round trip of about 60 km and from cold to back home it did not come on at all, ambient temp by the way was 16-22c, although this does not seem to be a factor. I have just ordered the new brake switch as reccomended above and will also change the relay as well. see what happens

cataha

What you needs to do is

http://www.modulemaster.com/en/wizard/index.php

Test the out put of your sensor "per website", then after you will eventually spend some like 100-200$ for repairing ABS modular since it a know problem.! good luck

The Joker

I have the same problem. I have noticed that it does not come on in the rain but if anyone figures it out please post fix. I have spent over a grand in parts and still no results.

povar

The brake light switch does not apply to non BAS equipped cars, and cars without a CAN bus.

95 S500

My ASR light (1995 S500)has been coming on when the car sits for a period of time, I think that it was a drop in battery voltage, because I let it sit for 3 weeks but disconnected the battery, and when I re-connected the battery, the ASR light did not come on and has not come on since. This is just a suggestion,you can check to make sure you do not have a current draw somewhere on the car,which may cause the ASR light to come on,the slightest drop under 12 volts will cause the ASR not to function properly,therfore it will illuminate.

doctorc

I was able to resolve my ASR/ABS light issue by removing and cleaning the modules in the Can. The light has not come back on since.

brandon101

Forgive my ignorance, but what/where is the CAN? I have the exact same issue with my 94 S350. The ABS light just started coming on after a couple of minutes driving, and the steering gets stiffer.

I also have the same SRS light issue that you described - it stays on for a couple of minutes before going out. Did cleaning the modules in the CAN as you described fix that issue as well? Did you unplug the battery for 30 minutes as was described in the thread?

Thanks for the help!

Phoenix

I had the same problem with my 94 S420, ASR/ABS lights came on, steering was a bit heavier then normal, same symptoms as described only my speedometer went dead as well when the lights came on.
had to change the front right wheel speed sensor and problem was resolved.
have the car scanned and see what code you get.

MichaelMcC

My S320 is having the exact same problem and I will try these fixes. But I also would like to know what the 'CAN' is that is mentioned several times.

Thanks

doctorc

The CAN that we are referring to is the controller area network (CAN) communication computer module system located under the hood on the passenger side of my S600. It has a black cover when once removed will reveal several computer modules. I removed each module and cleaned off any corrosion and used dielectric grease on all contact points. This fixed my problem, which had been diagnosed by my Mercedes dealer as as a bad speed sensor. My lights have been off since my original post.