W208 BAS ESP light on when brake is applied.

[Marty Y]

Hi everyone, I was hoping someone can help with this problem please?

After ten years of never having a problem with my W208 CLK 230 komp convertible (except a flat battery once) it suddenly developed a fault today when I was out driving in the middle of nowhere.

When I was driving along it beeped and BAS ESP warning visit workshop appeared on the display, I pulled off the road and switched off the car and then restarted it, the error message had gone but as soon as I put my foot on the brake it beeped and the error message appeared again! To make matters worse the car was stuck in park, I remembered that if you Insert a pencil or similar beneath position D in the gear shifting gate you can put it in drive again.

Everything is working ok, cruise control is fine and nothing else is wrong, except as soon as I put my foot on the brake when it's started the BAS ESP warning comes on and I have to unlock it from park.

Does anyone have any idea? I have read lots of old threads and seen some posts from television but I would like some advice before I take it to my non Mercedes garage for them to scan for codes.

Sorry for the long post on a subject that has been brought up lots of times before.

 

[ajlsl600]

Wheel sensor, reluctor ring? They do corrode

 

[Blobcat]

Brake light switch?

 

[Uncle Benz]

I’m with Blobcat, brake light switch first thing to check. It has two sets of contacts, so don’t assume it’s fine just because the brake lights are working

 

[malcolm E53 AMG]

^+1 - brake light switch - you don’t hear this very often nowadays for obvious reasons

 

[mioba]

Read the codes. A good code reader and user will pinpoint the issue. Throwing parts at it gets expensive.

 

[Marty Y]

Thanks for the replies!

I phoned the garage who does my MOT and has cleared a SRS warning light in the past for me, they said that the earliest they can scan it for codes is Thursday.

Once the garage has looked at it on Thursday I will let you know what the cause of it is, hopefully it is something straight forward like a brake light switch.

 

[Marty Y]

Update and conclusion.

I didn't want to drive the car whilst I knew that there was a fault with it, so it had been sitting in my garage, yesterday I had started it up while it was in the garage so I could check if the brake lights were working, the brake lights were not working at all.

I took it to the garage that does my MOT today and they have fixed it for £25 labour, no parts were required. I'm not sure that I completely understand what he meant but the mechanic said that the problem was more mechanical than electrical, the switch or lever that activates the brake lights was stuck in, he fiddled about with it and checked what he did had worked several times and it's okay now.

Thanks to everyone that replied to the thread with good advice, I'm very happy that my car is now working properly again and didn't cost a lot of money.

 

[malcolm E53 AMG]

Good to hear it was only the brake switch what I would do is go to MB and buy one they are <£20 the probability is that the switch will stick again it’s very easy to fit yourself or have the garage pop it on at the next service takes 5 mins to do

 

[Uncle Benz]

Sticking is what they commonly do. You can fix it temporarily with a squirt of WD40, but it will fail again. I’d recommend buying a spare, even if you don’t fit it right away

 

[Marty Y]

Sticking is what they commonly do. You can fix it temporarily with a squirt of WD40, but it will fail again. I’d recommend buying a spare, even if you don’t fit it right away

Is it a brake light switch that I should ask my local Mercedes dealership for?

I didn't even know that there was anything that moved or could stick on a brake light switch, I was under the impression that it was just a electrical switch.

Edit, after watching a video on YouTube, I see there is a white plunger looking thing that goes in and out, on the end that screws in, I can see how it works now.

I will take the advice of the forum and get one from Mercedes just in case it happens again.

 

[Uncle Benz]

Yup, you’ve got it!

I keep one in stock, even now they are becoming rare cars.

There are two types, so quote your chassis number when ordering. The round pin type are rarer