ML500 ESP/BAS Problem
 

Hello all, i have a 2002 ML500 which I have been having problems with the BAS/ESP warning light. I took the car to the dealer and the SDS returned codes C1000, C1042, C1022 and C1040. A new ESP/BAS control module was ordered and later installed. Fast forward one month. The light is back....intermitantly of course, about once a day after driving for a while. Took it back to the dealer today and when scaned with the SDS....no codes. Are there any faults that result in a code but get erased when the ignition is shut off? I love this truck but this is becoming a real hassle.

Your techs should know this already, but the stop lamp switch (about $25) will intermittently throw codes that will set off the ESP/BAS light. Also when it does, at least three codes get stored.

My 99 ML320 had this ailment, and the stop lamp switch replacement cured the problem.

This issue exists for other models as well. Just this week, I picked up my wife's 01 CLK from the dealer because it threw three codes and lit up the ESP/BAS light for the EXACT same thing. The fix? The stop lamp switch...

Thanks for your reply. The first time the car when in to the shop it threw the four codes listed. Most recently the light comes on but there are no codes stored. Since there are no codes, they say everything is "normal".

Yeah, the brake light switch is definitely the most common cause of ESP/BAS malfunctions, but it will store a fault code. One of the lesser known culprits is the vehicle battery. I've had a handful of stubborn cars over the years that gave VERY intermittent ESP/BAS warnings. All other electrical functions were normal. In these cases the warning lights came on immediately following engine start. Switching off the engine and re-starting caused the lights to go off. I don't know if this information will help, since you say the light comes on after driving for awhile, but it's easy enough to check. Good luck

Brake light switch......... easy DIY http://www.benzworld.org/forums/w163-m-class/1166641-ets-bas-warning-light-fix.html?highlight=brake+light+switch :thumbsup:

brake lite switch
 

just make absolutely sure that you buy a genuine switch from the dealer.you will regret it if you don't.

They checked the brake light switch adjustment and said if the switch were faulty it would have set a code...or is there an instance where the switch will trigger the light and not set a code?

Also on the owrkorder they checked voltage supply and the battery. Just a thought....could a bad alternator/voltage regulator cause this issue?

Update- I was driving to work and the warning light appeared once again. This time I called the dealer and they said to drive over and to not shut the car off. They hooked the SDS to the car and a code indicating the Steering Angle Sensor is faulty. The strange thing is that when we shut the car off and restarted it....the code was stored. I hate when "black magic" is needed to fix my car. Anyway, the part is ordered and by Friday it should all be fixed.

Ha, ha, it's not " black magic ", it's " modern technology ".
These things are supposed to prevent idiots ( that should'nt have a drivers license ), from wrapping themselves around a tree. ;)

An fyi for the future...if you ever disconnect the battery, that same sensor will have to be reinitialized when you reconnect the battery. You'll see the ESP/BAS light come on at startup until you turn your steering wheel lock-to-lock, then the light will go off.

This is normal MB behavior and should be outlined in the owner's manual.

Thanks, good information to have. I think there must be a flat spot in the sensor because it seems the truck is always making a slight curve to the right when the light pops on.

Okay, the story continues. The steering angle sensor is changed today (steering column replacement). After ten minutes on the road...you guessed it...the light returns. Ther is one road which almost always sets the warning light so I think I can eliminate the power relay. What I am convinced is that we are dealing witha bad sensor (sideway acceleration. yaw, or brake pressure) that is causing other items in the system to set a code. I am beginning to lose my patience with this truck and dealer. Anyone know what other sensors are in the system and where they are located? Thanks.

esp/bas
 

before you get pissed off just replace the brake lite switch.all of $17 part.it is so common that good dealer service advisors can do it in the service drive.there are 6 pins on the switch and only 2 of them handle the brake lights.for what this switch does it was a poor design and the aftermarket ones are junk.