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Discussion Starter #1
Recently for the first time ever on my 2000 ML430, the BAS/ESP representing the brake assist system and the electronic stability program came on when I was driving the vehicle in the rain. It stayed on until I shut the engine off after driving it several miles. When I restarted it the light was off, and I drove to the next destination without it coming on. However, after leaving there, it still raining and the roads still very wet, I drove a short distance and it came on again and again it stayed on until I shut the engine off. Drivning when it's dry does not cause thelight to go on. When it is dry the li9ght is off and doesn't come on. The tires are worn but not quite down to the treadwear bars,s so they have a little life and I have not noticed any slippage during the rain that I could feel. I've had this vehicle for several years and this is the first time the light has ever come on and I'm unsure how to interpret it. In my other vehicles a similar light comes on if a system activates, but goes off as soon as it returns to normal. If a light stays on I think it means there is an issue with one of the systems, but it doesn't stay on as discussed above, once the engine is shut off, apparently resetting.
I looked in the manual, but am still confused. My initial thought is perhaps the worn tires are slipping just a little and the ESP system is overly sensitive? I don't drive it agressively. Anyone offer any thoughts or encounter something similar?
 

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Dallas, Texas
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Normal telltale that system is helping you is blinking triangle on speedometer. Any other lights signal that there is problem somewhere. Brake light switch is most common but there are many other possible problems.
 

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2002 ML55 AMG, 2005 Chrysler Crossfire Coupe Limited, 1999 C280
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Witek has pointed you in the right direction.

As a first cheap and easy step, change your Brake Light Switch - It's a DIY and there are posts here with pictures as to how to change it.

It costs approximately $15 at the dealer.

IF the light persists then the 'fun' really starts - I see you are new here but if you do a cursory search/sample of posts on this Forum you will see it is one of the most common problem ML owners face.
 

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Discussion Starter #4
ok, so you guys are saying this is related to the brake assist system and not the ESP. Or at least it's the place to start. Thanks. I still don't understand it indicating a problem only when its raining and the street is wet. Any thoughts there?
 

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1999 E55, 2001 E320, 1990 560 SEC, 2004 ML350, 2001 ML55, 1995 S500, 1998 SL500, 2010 E550 Sport zoo
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What they are saying is that the most common problem is the brake light switch (buy the OE switch at the dealer, see the DIY at the top of this forum) and for $15-$20 and 20 minutes time you can see if that fixes the problem.

If it doesn't, then the next course would be to get a professional scan at a MB indie (whihc is less expensive than at the dealer) and that would give you the specific faults.

A generic code reader won't read the MB proprietary/deep codes for this type diagnosis.

Yes - it could be a faulty lead at a sensor, but then again most commonly it could be the brake light switch starting to poop out. The fault/sensor would be picked up on the scan. My thought raining, people instinctively start "riding the brake" pedal a little more than dry conditions.

$20 and 20 minutes to eliminate the simplest cause is the first step, if that doesn't do the trick then you move up to a scan which in most cases is next expense level up.

Keep the faith !

Also, I have known failing batteries to start doing wierd things in ML's when they drop below nominal voltage on the way out.
 

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2002 ML55 AMG, 2005 Chrysler Crossfire Coupe Limited, 1999 C280
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ok, so you guys are saying this is related to the brake assist system and not the ESP. Or at least it's the place to start. Thanks. I still don't understand it indicating a problem only when its raining and the street is wet. Any thoughts there?
The BAS, ESP and ABS all form part of the truck's traction control system and a malfunction in one of those features can trigger the lights you have.

This is why it's difficult to pinpoint which one of those features is malfunctioning and causing the lights to illuminate.

If after changing the brake light switch the problem persists, you will need to get a professional scan of the truck so as to avoid you groping in the dark as to which feature is faulty and needs a replacement part costing you $$$$.

In my opinion, I believe that the facts your lights came on a few times when it was wet/raining is purely coincidental.:)
 

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1999 ML320
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I have this issue for about one year so far.

First step - I changed the Brake light switch. It did not help
Second step- Cleaned all the speed sensors. Again the same issue.

Third step- I went for a $ 90 diagnostification and the code is:

C1142 B24/2 ESP Lateral Accel. sensor.

Symtoms: On slow sharp turns speed 30-50 miles/hrs, ESP triangle Light flashing and e-breakes apply. After that BAS/ESP light is on.

I am shopping around for this sensor, It is around $100
 

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Discussion Starter #8
Thanks to all of you for the replies- they are very helpful. Tomorrow will be rainy so we will see if the light comes on. I have not been able to get the light to come on when it is dry but will try harder to see if I can make it happen at my next opportunity. Right now though, it's too easy for it to happen in the rain and so I am having a rough time believing it to be coincidental (but it may be). I'll keep you posted until the problem is resolved. I assume that when the light is off that everything is functioning normally.
 

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Discussion Starter #9
No new incidents, rain or no rain. So I don't know. For a while it used to have the lights go on signaling the passenger airbag was not working when someone sat in that seat (not every time, but from time to time) and now it never does that anymore. The lights come on signaling everything is working correctly when you first start it up, and then they go out just like they are supposed to. Maybe it's just another German glitch. As they say at the car dealerhips, they can't fix something that is working right at the time you take it in. Will just monitor for now and see if it comes back! Thanks again for all your helpful insights.
 

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2001 ML55
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64 Posts
Would that "brake light switch" generate a fault code related to brake light switch ?

Because i have the same intermittant esp/bas light coming on. Mostly in very sharp turn, i have the esp/bas kicking in and ecu cutting power on engine...very disturbing and look pretty stupid in town :(...

I got code from lateral accel / yaw rate sensor stored, but got quoted like 1000$ for that sensor ? Where did u find it for 100$ ?
 

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I have my ML for years, and the "bas/esp" light has turned on twice for me. I changed the brake light switch and it fixed the problem both times. The reason why the light is on is because the brake light switch is frozen due to constant usage. Because its stuck, thats why it gives an error, your cruise control should not work, and possibly brake lights not working as well. These are signs that it needs to be changes, costs only $25 and takes less than 10 mins to change.
 

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1999 ML320
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154 Posts
Would that "brake light switch" generate a fault code related to brake light switch ?

Because i have the same intermittant esp/bas light coming on. Mostly in very sharp turn, i have the esp/bas kicking in and ecu cutting power on engine...very disturbing and look pretty stupid in town :(...

I got code from lateral accel / yaw rate sensor stored, but got quoted like 1000$ for that sensor ? Where did u find it for 100$ ?
What codes did you get?
Lateral accel & yaw rate are two different sensors(I mean for my car, I am not sure about ML55), so you should have two different Codes
 

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1999 ML320
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154 Posts
I have this issue for about one year so far.

First step - I changed the Brake light switch. It did not help
Second step- Cleaned all the speed sensors. Again the same issue.

Third step- I went for a $ 90 diagnostification and the code is:

C1142 B24/2 ESP Lateral Accel. sensor.

Symtoms: On slow sharp turns speed 30-50 miles/hrs, ESP triangle Light flashing and e-breakes apply. After that BAS/ESP light is on.

I am shopping around for this sensor, It is around $100
Replaced it, see the location

SAM_0007.jpg
 

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2000 ML430
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22 Posts
Witek has pointed you in the right direction.

As a first cheap and easy step, change your Brake Light Switch - It's a DIY and there are posts here with pictures as to how to change it.

It costs approximately $15 at the dealer.

IF the light persists then the 'fun' really starts - I see you are new here but if you do a cursory search/sample of posts on this Forum you will see it is one of the most common problem ML owners face.
Can someone help me fing this DIY for changing the brake light switch. There doesn't seem to be a sticky and I've searched quite a number of related posts. I saw a DIY video on this a while ago, but can't find it again.
 

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2000 ML430
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Awesome. Thank you bula. Turns out I bought the wrong switch. For a second, it looked like I could take the white piece off and put in on the new one. Didn't work. oh, well. At least now I know my way around a bit.

When I took the panel off this module looking thing was dangling there. a bunch of wire harnesses hooked up. I'll post the picture.
 

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99 ML430, 00 ML320, 05 E500 4matic Wagon
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scratchtopaz,
I am getting "invalid picture specified" error when trying to parse the link.
 
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