W211 left break light stays on

[IM2QT]

In my W211 left break light is constantly on. Everything else is completely fine. Car was at mechanic 2 times yet problem still remains..... Anyone may have a solution to this?

 

[richard]

Probably a failure in the rear SAM ... I would try disconnecting the battery (if this has not been done already) for 5 mins (just disconnect the brown earth lead)

But, the light is connected directly to the SAM and the wiring from that lamp to the SAM is not very long and unlikely to get damaged.

In Star Diagnosis you can turn on/off individual lamps to test, and it does detect power fed back up the line (i.e if something is shorting the wire to positive)

Richard

 

[BlackC55]

+1 for rear SAM fault

 

[Ted]

+2 Rear SAM. Really unlikely to be anything else.

 

[lisa110rry]

SORRY! HAVE JUST REALISED I HAD MIS-READ THE QUESTION - THOUGHT IT WAS THE WARNING LIGHT THAT WAS ON!

Hello, I don't really know what a rear SAM is, nor can I actually identify a W211, so I've been toying with whether to post this, but here goes.

I had a similar problem, had been to the garage about it three times, but still after driving a while the brake light indicator would come on - even though the brake lights were actually working.

First, by reading the manual, I discovered that once that light had come on it would remain on until the car was switched off.

Taking the car back to my local garage (not MB) a young mechanic said he knew what it was. He showed me the lights from the inside and showed me some plastic "nibs" that held everything in place. These had softened with heat and years of braking and thus the lamp holder had become loose. He wedged something underneath so that it couldn't move and it was all fixed!

Now my car is 15 years old, think how many times it has braked. Could well be something else on yours, I'm quite sure.

Regards,

Lisa

 

[BlackC55]

SORRY! HAVE JUST REALISED I HAD MIS-READ THE QUESTION - THOUGHT IT WAS THE WARNING LIGHT THAT WAS ON!

Hello, I don't really know what a rear SAM is, nor can I actually identify a W211, so I've been toying with whether to post this, but here goes.

I had a similar problem, had been to the garage about it three times, but still after driving a while the brake light indicator would come on - even though the brake lights were actually working.

First, by reading the manual, I discovered that once that light had come on it would remain on until the car was switched off.

Taking the car back to my local garage (not MB) a young mechanic said he knew what it was. He showed me the lights from the inside and showed me some plastic "nibs" that held everything in place. These had softened with heat and years of braking and thus the lamp holder had become loose. He wedged something underneath so that it couldn't move and it was all fixed!

Now my car is 15 years old, think how many times it has braked. Could well be something else on yours, I'm quite sure.

Regards,

Lisa

Its a very different set up on a 211.

 

[IM2QT]

So... what exactly should I do to fix it? Disconnecting battery doesn't help.

This whole thing began when right running light stopped working. I read somewhere that break lights takes over running lights functions when they are broken. But this running light was replaced and now everything should return to normal, but for whatever reason this break light stays on forever, even when the engine is gone.

 

[BlackC55]

Take it to someone with a Star that knows what they are doing.