hello everyone, I hate to keep beating a dead horse but here goes. I have ASR and ABS lights on and I don't have the limp mode issue like others with ASR light on. My car runs fine I can go triple digits in my 97 S500. I KNOW THE BEST WAY TO find what the problem is to check codes, but before I do that, I want to replace the stop light switch in the brake peddle first, then if needed I will clean or replace the ABS speed sensor. if both will not remedy the problem then I am in for some serious $$$$$$$$ repair? I read in the thread that the way to test a broken stop light switch is to press on the brake peddle , then start the engine and wait for a few minutes =, then let go of the brake peddle. If the asr and abs lights come on after you do that, then the stop loght switch needs replacing. Can anyone verify this information. I have followed these proceddures and it seems correct. If I start the car without having pressing the brake peddle, then the light would turn on immediately. I search every thread relating to asr abs and could not find the information I have read earlier. I just want to know if there is a way to check a broken stop light switch.

I believe there is a fault code for bad brake lamp switch - there was on earlier cars. I have always just replaced it - it's like a $15/15 minute item.

Shot gunning the brake light switch is not such a bad idea as they are cheap and fail regularly. There are FOUR speed sensors and they aren't exactly cheap, and they are only one possibility of what your problem could be.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

I will order the stop light switch soon and share my result in a later post. thnaks

There's a good chance it will be the brake light switch. I had the exact same symptoms as you... replaced the switch and presto, issue solved. Hardest part is getting the lower panel off the dash so that you can get to the switch. There are two catches at the front of the panel that are tricky to release unless you know where they are... so here's a picture of S500 when I took it apart... the front clips are circled in red and are hidden when the panel is in place. You release them with a fine tip screwdriver put between the carpet on the lower panel and the dash.
Also, length of the switch plunger is "automatic" in setting. Be sure to pull it out before installing. First time you step on the brake, it will adjust itself to the right length.
Hope this helps.

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KenP

1996 S500 W140 Coupe

Ken,
I had the exact same problem with my 93 400e (sold it last month) which had about 140k on it when the ABS & ASR lights came. It never went on the 'limp home' mode. It drove great but the braking went to a 'manual mode' meaning - the ABS wouldn't kick in. The braking was just fine. The mechanic said it needed a new 'ASR pressure pump'.

smk_texas
98 S420 50K

Hi Guys,

I am facing something similar. I have a mercedes s500 1996 model, it's japenese specs. The problem I am facing is, when I run the car after it has rested a while, the ABS/ASR light turns on, the steering wheel becomes a little stiff and the break works normally, though the car does not go into limp-home mode.

Please advise me as to what might the issue be? Is it a problem asking big investment? Or would it just be a problem of ABS pump/sensor etc? As I have read elsewhere that when the ABS malfunctions the ASR turns off automatically.

Now why is my steering becoming stiff? I don't understand that, and when I start it again after a while, everything is normal. Can anyone please explain?