Mercedes-Benz Forum banner

Yaw Rate Sensor and ESP/BAS light

281K views 187 replies 57 participants last post by  OldRetiredGuy 
#1 ·
My 2001 ML 320 is having the ESP/BAS light problem, accompanied by four episodes of the car locking up one of the wheels as though the ESP thinks we're going into a spin (even though we may be driving at 30 mph on a straightaway). I took the car into the dealer, and intially got a computer code indicating a problem with the ABS pump -- which I didn't believe, because that shouldn't make only one wheel lock up. After a week or so, when the problem recurred, I returned to the dealer; and this time the code indicated a bad yaw rate sensor -- which makes more sense to me: if the yaw rate sensor is feeding bad data to the computer, the car thinks it is going into a spin, and engages ESP.

The dealer wants over $1000 to fix the yaw rate sensor ($500 for the part plus labor). I want to DIY, since I read in this forum the part is plug-and-play.

Anyway, in reading old posts on this forum, it appears that the ML 320 has (at least) two kinds of sensors, a lateral acceleration sensor, and a yaw sensor. I have seen the part number 163-542-06-18 posted for the lateral acceleration sensor, but also part number 163-542-23-18 on a different post (an updated sensor?). But I haven't been able to find the part number for the yaw sensor.

Does anyone know what is the correct (and most current) part number for the yaw sensor? When I open up the center consol (I believe the yaw sensor is under the window control switches), will it be obvious which unit is the yaw sensor, and which one is the lateral accelerometer? And how, by the way, do you actually open up the center consol?

Thanks!
 
See less See more
#2 ·
I've been having the BAS/ESP light problem too (probably for more than 10k miles now). It does not affect the driving behavior of the car though. The light only comes on when when making slow turning maneuvers like parallell parking or making a U-turn. Once you're on the freeway orso, it turns off.

Any idea if this will affect the driving at some point? I have a feeling it's just some kind of sensor going bad making the light come on. Not sure though...
 
#4 ·
The BAS/ESP light problem can go on for quite a while without any symptoms (e.g. the brakes engaging suddenly). In fact, if it weren't for the fact that I've actually had the ESP kick in out of the blue -- thus scaring the daylights out of my wife and me -- I would have just left the dashboard light alone.

My MB dealership told me "When the light goes on, it indicates the computer has detected a fault in the system. It doesn't necessarily mean the computer has shut down the ESP, or that BAS or ESP will not engage when needed." In other words, a faulty wheel speed sensor, ABS pump, relay, lateral acceleration sensor, yaw sensor, or brake switch (or any number of things) will make the light go on -- but ESP is not turned off unless you manually turn it off.

My guess is that, in my case, the light goes on when my intermittently faulty yaw sensor sends a bad signal to the ESP system. Unfortunately, sometimes the ESP thinks the bad signals are real signs of a spin, and the ESP engages. Of note, when I turn off the ESP (using the ESP OFF button on the dash), I don't get the dashboard ESP/BAS light, and I don't experience the sudden braking from ESP. I suppose that should make sense.

I'm still looking for that part number, though!
 
#8 ·
I think I'm having the same problem, it just started. If I go into a sharp corner occasionally the ESP comes on. This started after I put too much air into one of the rear tires so I backed it down to the same preasure as the opposite one. It's really strange, I'm running a 2001 ML55.
 
#13 ·
Dting22, I have no solutions for you because my BAS/ESP/ABS.../XYZ lights haven't graduated to lock-up yet. Let us know what the solution is. it's a very scary problem. I know that last year another forum member had this problem and I don't recall whether or not it was eventually resolved. Please let us know as you make progress. There could be several solutions, like many ML problems are!!!!! Thanks.
 
#16 ·
Just to update this thread, I am a mechanic here in New York, I have a customers car which is a 2000 Ml320. They brought the truck to me cuz the brakes would ingauge for no reason. After scanning the car with my Launch X431 it cam up with c1120 (Rotary stored speed and lateral acceleration sensor): Signal cable has open circuit or short circuit. After a little research I replaced the yaw sensor (which is located in the center console under the window switches) and the problem was gone but with a little twist. It would not lock the brakes anymore but from time to time the bas light would come on.
After inspecting the vehicle I noticed a broken wire in the rear of the truck on the passenger side right above the axle. Now, I am not sure what this wire is for. The end of the wire has no connection (looks like it broke off) and there is nothing in the back that is missing a plug. There are three wires in the loom and it was constantly rubbing on the axle. I believe this is what was causing the BAS light to come on. Since tapping up the wires the light has not come back on. So for anyone having this problem I would sujest you make sure no wires are broken or touching anywhere.
 
#20 · (Edited)
Enrike - can you PM me what you did or post it here... I have been dealing with some annoying issues for a while that is either a wheel position sensor, lateral acceleration sensor, or yaw sensor.

Issue A. (more frequent)
I get the abs pumping the brakes when i am coming to a slow stop. Like as if the road is really slippery. Doesnt happen as often when coming to a hard stop mostly a gradual stop. This sometimes triggers all three dash lights to come on and stay on but not always... and i can clear them after a few ignition cycles.

Issue B. (less frequent)
I am crossing an intersection for eg.... the /!\ yellow triangle light will flash and i wont be able to accelerate for a few seconds. It doesnt seem to be when I am turning left but going straight. It feels like limp mode or the computer is cutting the throttle. It only lasts a few seconds but could be very dangerous. This happens several times per month and is worrisome. It doesnt always trigger the three warning lights to come on.


So I am wondering if I have more than one issue. One theory I have is the wheel position sensors are dirty or faulty and that is Issue A. And the lateral acceleration or yaw sensor is 'Issue B.' I just don't know and I havent had a chance to dig in to it yet.

Any ideas ladies and gents?

(PS - I have already changed the brake light switch)
 
#22 ·
no they all have decent thread.. but one is a goodyear forterra and the others are dueller alenzas.
 
#24 ·
yeah.. i just had a damaged tire and didnt want to buy a new dueller when the others are at 50% and I couldnt find a used one.. You think all of my issues would be attributed to a mismatched tire? The overall diameter, weight and tread is relatively similar.
 
#25 ·
Check to see what code you're being thrown... if it's the lateral acceleration sensor, order Part no: A163 542 06 18 002 ($100 is a good price)

Here's a photo of what it looks like... Pull out the plastic "bucket" of your armrest console, and it's just underneath.

 
#27 ·
It's not fixed because you changed out the wrong part...

The code tells you the lateral acceleration sensor is bad. You said so yourself. What did you do? You opt out of the $100 code-verified solution and you jump on the $400 shotgun blast in the dark (aforementioned reference to firearms dedicated to Witek1 and 43sqd).

There are a lot of other threads on here about the spontaneous activation of the brakes, combined with the BAS/ESP light.

Do yourself a favor. Buy the darned lateral acceleration sensor for $100. Replace it. If it doesn't fix the problem, and you come back to us with actual proof that your scanner is lying to you, put the sensor on ebay. As you can tell from the other threads on this forum, this is a common enough occurance that somebody out there will buy it and you can recoup your hundo.

Or, you could replace the ABS Pump, all of your pads and rotors, your AAM, and maybe your stereo. It won't solve your problem.

We're here to help, but when you tell us that your vehicle is "meowing," so you're going to run out to buy dog food, you've got to expect somebody to point out an apparent error in judgment. It's not meant to be rude, it's meant to get you running right again.

Cheers!
 
#31 ·
Ok, no need to be rude. maybe i was not clear when i made my post but the lateral wheel sensor was changed first, and the problem persisted. so then after further research i changed the yaw sensor, which stopped the locking up but the bas light still comes on when going over a pebble. so yes i did replace what the fancy computer told me to and that did not help. and the yaw sensor was only $85. wheel speed sensor $65.


cheers
 
#28 ·
ruff talk - well i think that might be my problem. Found the part for $91.
 
#29 ·
My sharp-tongued (but intended to be helpful) rant was not directed toward you, pdx.

It was for the guy directly above the rant.
 
#30 ·
"ruff" talk - i was being too subtle... playing off your cat and dog metaphor.. i get it :) Appreciate your disclaimer though my good man.
 
#32 ·
OK look, dude.

First of all, you're a mechanic. I am not. I can fix stuff on my truck based on my experience with pulling apart old jap bikes when I was younger because I simply couldn't afford to pay somebody to do it back then.

And seriously, diagnostic skills? Not me, man. Not on a machine with which I'm unfamiliar.

Also, I wasn't, nor am I now, trying to be rude. I'm TRYING TO HELP YOU. I'm sorry.

However, that being said: I have provided you with a part number, I have provided you with a picture, and I have provided you with an explanation of where the part is located in the vehicle.

If you are confused as to which part your scanner is telling you to replace, that's completely understandable. But I am providing you with clear, concise advice based upon what you yourself said regarding the codes thrown, and the description of the problem your scanner provided.

So, if you have actually purchased and replaced the part I documented, described, and photographed, we're good. And if my solution didn't work for you like it did for me and quite a few other people here, then hey, tell me my interpretive skills blow. It's all good.

Since you're a mechanic by trade, you see a lot of different stuff on a lot of different cars. You're giving me names of parts you say you've replaced that don't actually exist. (i.e. lateral wheel sensor) Can you blame me for thinking you might be a bit confused? Can you blame me for trying to pound my point home by breaking your balls a little?

I don't see a lot of different stuff on a lot of different cars. Every day, I see the same vehicle. I'm married to it. I feel it speak to me when I'm on the road, and I can sense issues with it that other people can't. I've developed a relationship with it, just like other people have developed relationships with their ML's. And I'm telling you... We're good at what we do here.

So take a deep breath, please accept my apology for making you feel like a person less than your actual station, and let's fix this bitch.

Buy the LATERAL ACCELERATION SENSOR, as described, documented, and photographed above. It AIN't in the wheels. It's right next to the pretty little yaw sensor you blew all of your money on. :)

Good luck Bro. We're here for you. :thumbsup:
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top