Asr/bas Warning Light.

[NICK L]

Hi All,
I'm new to the Forum and MB Ownership, I have just taken delivery of my C240 Sport Auto Estate and yesterday as I pulled away from the kerb I slowed down and the ASR/BAS warning light came on so I pulled in after about 50 yards and turned off the engine.
I started the car again and the light went off as per usual and has not come on since, could this simply be dirt on a sensor? or something else.

Many Thanks,

Nick.

 

[peterchurch]

Mine did exactly the same thing a few days ago, it was very hot at the time so I put it down to heat...

 

[NICK L]

Thanks, I have been out in the car today and sign of the light so lets hope all is well.

Nick.

 

[pascal]

This is weird.

On one of the real hot days (10 days ago). I 'tore away' at a st of traffic lights. Almost immediately the ABS & ESP/BAS lights came on. Next set of lights, turned engine off for a few secs, and when I re-started, all was fine and still is.

Pascal

 

[peterchurch]

This is weird.

On one of the real hot days (10 days ago). I 'tore away' at a st of traffic lights. Almost immediately the ABS & ESP/BAS lights came on. Next set of lights, turned engine off for a few secs, and when I re-started, all was fine and still is.

Pascal

oh goody a feature

 

[jberks]

This is usually the brake light switch. Very common fault. If so it will probably happen again and get more frequent. A new switch is £6 so nothing to worry about.

 

[996jimbo]

On my way in to work this morning (late again) braked late for a roundabout from high speed and noticed shortly after that my ABS and BAS/ESP lights were on. Can't be sure but I assume it was the braking rather than subsequent gentle acceleration that brought them on.

Stopped, switched off and then restarted. Hey presto! Just like everyone else above, lights off.

Cruise control also seemed not to be working although speed limiter was working.

 

[jberks]

brake light switch it is then.
(speed limiter doesn't use it - everything else does.)

 

[996jimbo]

What's wrong with the brake light switch and why is it making the ASR etc lights come on? Are we talking the little plunger thing? Is there a little plunger thing as I haven't yet tried to contort myself upside-down into the footwell.

 

[Nidge]

This is weird.

On one of the real hot days (10 days ago). I 'tore away' at a st of traffic lights. Almost immediately the ABS & ESP/BAS lights came on. Next set of lights, turned engine off for a few secs, and when I re-started, all was fine and still is.

Pascal

Blimey there's an epidemic- exactly the same thing happened to me, I reversed out of the drive quite quickly, put it into drive and imediately the BAS and ASR warnings flashed up on the display (one after the other). I stopped, switched off and restarted and all was well.

 

[jberks]

Jimbo,
I can't say I know exactly how it works, but yes, its the little brake plunger switch at the top of the pedal. The computer needs to know when and how hard you are braking in order to judge whether all is well or it needs to step in and help. If it can't tell, it will shut down the ABS, ESP and BAS as a precaution. Its quite a common failure and it shows up on the diagnostic computer log so easy to diagnose. If the warning comes on when braking, this is the normal cause. As its an intermittent fault, resetting the ignition will clear the lights until it detects the problem again - often not for several weeks. Its cheap enough so I replaced mine a few years ago, and not heard from it since.
Another cause if you are menouvering a lot can be the steering wheel position sensor getting confused. That is cured by turning lock to lock a couple of times, and the warning light goes off again.
Clearly there can be other causes such as wheel sensors etc but the switch is by far the most common.

 

[cobra427]

Same symptoms for me during this last hot spell also.
ASR/BAS light comes on - generally in hot weather. Cruise stops working - limiter is ok.
It sometimes comes on at switch on. It NEVER comes on if i've pressed the brake pedal before starting.

 

[gpilko]

Just to backup what jBerks said - I had a similar problem with the BAS/ASR light coming on last week on my SLK. Turned out to be the brake switch (surprise surprise) which was replaced by local independant. Problem curred and hasn't been back since.

ABS light did not come on though, not sure if this is the same with all models? If the ABS and ASR lights are on I may be more inclined to think wheel speed sensor.

All in all it cost £38 to fix, so not a major job

Guy.

 

[NICK L]

Hi All,
Light came on again yesterday and reset again when I restarted the car, going back to the dealer tomorrow to have it fixed so hopefully this will be the last I see of it.

Nick.

 

[996jimbo]

Do post what the answer to yours was - mine comes on every morning now, but does not come on at lunchtimes.

Hopefully it's the plunger as per jberks advice. I'm trying to generate the enthusiasm for the necessary effort to locate it but have so far failed.

 

[NICK L]

All Fixed!

Hi All,
Just collected the car and it was the switch, this has been replaced FOC and now all seems well!
Thanks for all the advice, the dealer was surprised I knew what the problem was, I simply said it's all thanks to the MBOA!

Regards,

Nick. :wink:

 

[The physician]

abs bas warning lights

Please help! Intermittent bas abs and ecs warning lights come on, all together, no obvious reason. Restarting solves the problem with 'no malfunctions' displayed--- until the next time!

 

[996jimbo]

As a follow up: Mine was down to the brake switch. Had it replaced and no more lights on.

It started as an intermittent fault with nothing obvious causing it (didn't relate to using the brake at all) and became more frequent.

Sorted.

 

[jberks]

Please help! Intermittent bas abs and ecs warning lights come on, all together, no obvious reason. Restarting solves the problem with 'no malfunctions' displayed--- until the next time!

I think you already have the answer as above. Either replace the brake switch or get the fault code off the diag computer for £60+. For around £8 for the part and 2 mins to fit, probably worth the risk of getting it wrong.

 

[alec]

BAS problem

There is a known problem on some c class models in the early 2000's.
Can affect cruise control and seems like brake light switch.
But brake light switch is not conventional.

Soloution is a wiring modification, your dealer can check this from the fault codes.

Alec