Big Problems with ML320 Pls Help!
 

Hi everyone, I am having big problems with my ML, it is a 2001 and it only has 54K miles. Anyway, going down the road, at about 35 MPH the breaks came on by themselves!!!, It was weird cos then a bunch of lights came on ABS/EPS and the little triangle in the middle of the dash came on. I tried to speed up but the engine would go above 1000 RPMs, and everytime I tried the breaks came on again, that happened 3 times and then the lights stayed on and I was able to drive it like nothing had happened. I took it to a shop immediately and all they did was change the break light switch because apparently one of the codes was for that switch. They also had codes for a yaw switch but that part it 3000 dollars!! and they wanted to try the break light switch first, I have driven it for 200 miles and it hasn't done it again but I am afraid I'll go down the highway doing 55 mph and the breaks will come on. Please tell me if you have heard about this problem and what fixed it, the mechanics nor the dealer here knew what to do. Thanks a lot

Have heard of this but its quite rare. Perhaps if you do a search on this forum you may find something. If I remember correctly it was a bad sensor that caused the problem and I believe it was the yaw sensor. The brake light switch will cause the ABS/ESP lights and perhaps some other stuff like cruise control being inop but not the brake application that you mentioned. If it happened once it is likely to happen again and it could be a real hazzard. Get it diagnosed and corrected.

Scare to drive
 

It actually happened twice that day. First I was doing 35 MPH and the breaks came on, engine slowed down and wouldn't go higher than 1000 Rpms. It was dangerous. Then, once the lights stayed on (ABS/ESP) the car was ok to drive. I drove for 20 minutes, parked it and came back after an hour and the light was not there anymore. I drove it for about 2 miles and then the same thing happened again, the breaks came on and the engine slowed doen below 100 Rpms and everytime I tried going faster to pull over the car would apply the breaks, and then the lights stayed on and it was ok to drive. I took it to the shop and told the guys that I couldn't come up with a single common thing between both scenarios. The first time: 35MPH, even road, no debri on the road, no rain. The second time: 45MPH, entering a curve, no rain, no hot weather. Again, they only replaced the break light switch and I don't know what to do because even though the car has been driven over 200 miles and not done it again, what if it does it again??? Where can I go to figure out this problem?? the dealer here in Oregon doesn't know what the problem is either and if I bring it in they'll just throw parts at it and charge me millions for it. PLEASE HELP!!!

Like Sosh suggests....
 

most likely a yaw sensor problem, relatively easy to get to, but expensive - more so if it turns out not to be the problem.

Just one of the joys of owning an ML with all its electrical gremlins....

Has your dealer run a Star system diagnosus?? Faults will be usually stored in the system even if they are intermittent. Also have them call MB tech services if they have a problem with figuring this out. Yaw sensor seems to be the likely culprit as I said before but get it fixed before someone gets hurt. You seem to be begging for help and you seem to have ignored my first post which also said yaw sensor. Talk won't fix it but an accurate diagnosis and repair will.

Thanks Sosh
 

I will get it diagnosed at MB and see what happens. The shop I took it to "cleared the codes" and I don't know if the star diagnosis will still get the codes out but I can always call the shop and have them give those codes to me and then give them to MB I guess. Thanks for your second reply, I will look into this problem before I drive it again.

Took it to the dealer
 

So I took my ML320 to the dealer. They scanned it but did not get any codes since the shop where I brought it to had scanned it and cleared all the codes. I gave the mechanics at the MB dealer the codes the other shop got:

Break Light Switch
Yaw Turn Sensor

and explained to them that all the other shop did was change the break light switch. The expert at the dealer said he's never heard of a problem like this and said that neither a break light switch nor replacing a Yaw sensor would ever fix a problem like that since, he said, neither could cause the ABS to come on. Their suggestion was to keep driving and wait until it happens again so they have codes to work on... Not really what I expected. How can I drive knowing the breaks can come on anytime and cause an accident or kill me!!! and besides, if it happens again I will probably get the same 2 codes the first shop cleared... I wish someone could help me on this one.

Thanks

Its quite possible that the dealer has not heard of this before as it is very rare. The dealer I use is huge and they have not ever had this complaint.
I would insist that they change the yaw sensor as it will cause this depending on how it fails. If you wait for it to happen again you could be putting yourself and others in a precarious position with possible injuries or worse. It will most likely happen again. Weigh the cost of the sensor which you know had a fault against the personal injuries that could result from another failure and the liability you could incur.

Sensor change
 

Got codes from the shop I originally took my car to, and brought them over to the dealer. He looked at them and pretty much insisted I should "wait" for the problem to happen again. I think they don't want to change a part without codes because they insist the Yaw Rate Sensor would not cause the problems I have. I have been thinking about it and I decided to change the Yaw Rate Sensor myself, does anybody know if these sensors need any "special reseting" after you put them on??? Sort of like reseting its values, or is it just a part you can swap with a new sensor???

thanks

Hey Enrike,

The same has happened to me. Was doing 70mph and it was quite scary, lucky lane next to me was clear and i pulled in to the hard shoulder.

It was an extremely windy day that day and the car was rocking a bit in crosswinds so i came to the conclusion that something about instability caused it. Especially seeing as ESP light came on.

Hasn't happened since. I still think it was something to do with winds.

Was it a windy day by any chance when it happened to you?

Winds would have nothing at all to do with this problem.

I would replace the brake switch first (common problem) and then see what happens.

ETS and crosswinds....
 

I have actually had the ESP light come on when an exceptionally strong crosswind gust hit my ML. I was travelling at some speed in an area known for gusts, and I figure the combination of speed, cross wind and road surface caused it to operate. In fact it was the I-8 leaving San Diego going through a mountain pass.

A little alarming at the time, but served it's purpose to remind me to slow down a little.

So it is possible, but maybe not of any significance in this case.

This is a common problem for 163's. When the ABS/ESP/BRAKE Warning, etc. all come on and you cant get out of 1st gear when stopped or in his case dont accel, its the ABS hydraulic unit. Some models you can get the control unit seperatly from the ABS hydraulic unit. Anyways, its around $1000 for control unit and $3000 for the Hydraulic unit which comes with the module.

If you are speaking about the yellow triangle it should only come on with wheel slippage which you may have had. But winds rocking the car should not do it unless it lightened the car to the point that caused at least one wheel to lose traction and slip.

Beg to differ with you unless one of us misunderstood the posters problem. I read it to understand that all the brakes applied themselves. This is a rare problem and could be caused by the yaw sensor failing. The lights coming on could be caused by a number of things like a bad sensor or the brake switch failing. I do not believe he needs a ABS/hyd. unit. I do believe the problem was caused by a bad yaw sensor. He also hade a code for the yaw sensor and the brake switch. He elected not to change the sensor but only the switch.

Replaced Sensor
 

So I finally decided to replace the Yaw Rate Sensor. The part for my ML 320 was about $500 but it's worth it. Peace of mind..... I will post here as soon as anything happens. If you don't hear from me it means the part fixed the problem. Thank you all for posting your comments...

Has this occured again after the YAW rate sensor was replaced?
 

I seem to have the same problem happening to me 2 months ago. Everything has been fine since but then it happen again today.

BUMP

any updates on this? Did you find the fault and fix it?

It happened to me again a few days ago. i am on holiday and all the local garages are closed until 2nd january so i am stuck here till then.

sosh, if you get to read this post, your posts above were very informative. i must do more research on yaw sensor.

i cant drive my ml now until i get t to garage but, when i turn ESP off the problem doesnt seem to occur, when i turn ESP back on the brakes come on again like op's problem.

but the thing is, when ESP is off the brakes are over sensitive and dangerous and car brakes and skids to the right at the lightest touch. is this normal with ESP off?


any info greatly appreciated.

ODI OPENED PE07-007 AFTER RECEIVING 4 COMPLAINTS WITHIN A 6 WEEK PERIOD ALLEGING INCIDENTS OF UNCOMMANDED BRAKE APPLICATION IN MODEL YEAR (MY) 2000 THROUGH 2001 MERCEDES M CLASS SPORT UTILITY VEHICLES. INFORMATION CONTAINED IN THE REPORTS OR GATHERED IN SUBSEQUENT CONSUMER INTERVIEWS INDICATED THAT THE INCIDENTS WERE CAUSED BY FAULTS IN THE ELECTRONIC STABILITY PROGRAM (ESP) SYSTEM WHICH WERE REPAIRED BY REPLACING THE YAW RATE SENSORS. ALTHOUGH THE SAME YAW RATE SENSOR IS USED IN APPROXIMATELY 800,000 OTHER MERCEDES M-CLASS, C-CLASS AND SLK MODELS, TO DATE THERE HAS BEEN ONLY ONE RELATED COMPLAINT TO ODI IN THOSE VEHICLES. DURING THIS INVESTIGATION MERCEDES BENZ PROVIDED ODI WITH 327 COMPLAINTS RELATED TO THE ESP SYSTEM IN THE MY 2000 THROUGH 2001 M CLASS VEHICLES. SEVEN OF THE COMPLAINTS SUBMITTED BY MERCEDES ALLEGED INCIDENTS OF UNCOMMANDED BRAKE ACTIVATION WHILE DRIVING, WITH TWO OF THESE INVOLVING VEHICLES IDENTIFIED IN THE ODI COMPLAINTS. NONE OF THE INCIDENTS RESULTED IN CRASH OR INJURY. HOWEVER, THE OWNERS DID EXPRESS SAFETY CONCERNS DUE TO THE SUDDEN, UNEXPECTED CHANGE IN VEHICLE SPEED AND DIRECTION. ON MAY 10, 2007 MERCEDES BENZ MET WITH NHTSA TO PROVIDE A TECHNICAL PRESENTATION AND CONDUCT A DRIVING DEMONSTRATION OF THE ESP SYSTEM PERFORMANCE WITH SIMULATED ELECTRICAL FAULTS IN THE YAW RATE SENSOR. MERCEDES SHOWED THAT THE ESP SYSTEM IS PROGRAMMED TO DIAGNOSE ELECTRICAL FAULTS AND THAT BRAKE APPLICATIONS RESULTING FROM YAW RATE SENSOR ELECTRICAL FAULTS ARE VERY SHORT IN DURATION (0.3 SECONDS OR LESS) AND DO NOT AFFECT VEHICLE CONTROL OR STABILITY. NINE OF THE CONSUMER COMPLAINTS TO ODI AND MERCEDES ALLEGED BRAKE ACTIVATIONS LONGER THAN 0.3 SECONDS, WITH SEVERAL ALLEGING THAT THE INCIDENT LASTED UNTIL THE VEHICLE CAME TO A STOP. A COMPLAINT VEHICLE THAT ALLEGED MULTIPLE INCIDENTS WAS EVALUATED BY ODI AT THE VEHICLE RESEARCH AND TEST CENTER (VRTC) IN EAST LIBERTY, OHIO. VRTC WAS UNABLE TO DUPLICATE THE CONDITION. DUE TO THE LOW COMPLAINT RATE AND ONLY ONE NEW COMPLAINT TO ODI OR MERCEDES SINCE JANUARY 2007, THIS INVESTIGATION HAS BEEN CLOSED. ODI WILL CONTINUE TO MONITOR COMPLAINTS IN THE SUBJECT VEHICLES AND OTHER MERCEDES PRODUCTS USING THE SAME YAW RATE SENSOR AND MERCEDES WILL PROVIDE UPDATES ON FIELD EXPERIENCE (COMPLAINTS, FIELD REPORTS AND WARRANTY CLAIMS) THROUGH THE END OF 2007.

Man that is cool, I thought I was by myself on this. I did change my Yaw Rate Sensor and it did fix the problem. I wish mercedes paid me back the 500$ + I spent on this.

More news
 

It has been quite a while since I changed the Yaw rate Sensor on my ML-320 and my car has been driving like a dream, no problems at all. I have driven my car in all kinds of weather (snows and rains in Oregon 24/7) and ABSOLUTELY NO PROBLEMS. Please have this component replaced if your car's brakes ever happen to come on by themselves, this is a REAL BIG problem and I can't believe it has happen to so many people and MB still doesn't want to make a safety recall on this.
Feel free to ask any questions.

your right but although a very serious problem its a rare problem, we are the unlucky ones!

At least people have this thread for reference now when it happens to them. It took me months of research to find what the problem was.

I'm not having any problems yet, but this is a good reference for others to check.
Where is the location of the yaw sensor(s) you replaced?

Yaw Rate Sensor
 

The Yaw Rate Sensor is behind the center console. I did not replace the sensor myself because the computer has to be reprogrammed for the new sensor. I debated about doing it myself for a while because some people said you could just replace it. Another guy told me you had to reprogram the computer... It took me a while to make a decision and remembered how scarry it was to have the breaks come on all of a sudden so I paid 500 for the part and about 100 for labor... It was a lot of money but that is the price of safety.

i heard of the opposite way of this, lol
that it Gases to 50 km automatically lol
happen to my buddies old C class

Photo of yaw rate sensor
 

Hi Enrike,

Just would like to confirm the attached photo is the one you talk about. I had the same problem as you described and my mechanic told me to replace this. Tks. :)

What is that?

Have you had any problems with the brakes doing that anymore? I'm having the same problem and no one knows what to do! Also, how do we get Mercedes to do a safety recall on this problem?!!! It's scary!

hey everyone
 

Ivan 318 that is indeed the Yaw Rate Sensor

and so everyone knows, I have not had the problems I had before ever again. Changing the Yaw Rate Sensor fixed the problem...

later

Thanks for the very timely update. I am trying to purchase my first ML, and I was looking at both a 2001 and a 2003 ML320. Since it seems the yaw sensor problem was a 200-01 issue, it makes the choice a lot easier!!! The o1 is at the MB dealer, so maybe I can work a deal to have them replace the sensor if I buy the car. ;)

Sudden Braking w/o warning
 

I've had the same thing happen to me. Originally replaced the brake light switch and then braking happened again. When I took it into the shop (private) the ODI showed faulty fuel level indicator, faulty map code and O2 sensors. I replaced the first two items and the O2 cleared out. The very next day out of the shop the car stopped dead in its tracks again. The technician did not find any codes what so ever, so I will look into the Yaw sensor mentioned above. If anyone else has experienced this condition or can offer any suggestions please post.
thanks,
d2ml320

This is really insane. I've had lots of people contacting me over the past few years since I started this thread, asking me questions about the very same things I experienced. I just hope there isn't people out there who didn't get a chance to post because they got involved on an accident. If anyone out there knows of a way to change the title of the thread so it is easier for people to do a search and find this thread I'd appreciate it. I don't think the title is helping people with "sudden braking" find this very helpful thread... FYI I'm still driving my ML320 and have had no problems ever since I changed the Yaw Rate Sensor.

Brakes_Repeat Problem ML320
 

I have owned my 1998 ML320 since new. At 72,371 miles the right front brakes dragged severely to the point the car was pulling right and the pads smoking. Replaced all parts, calipers, rotors, pads on both left and right front. Did everything dealer recommended.

Same problem occurred again yesterday at 81,895 miles. No indicator lights either time. This is dangerous.

Car has been dealer maintained on schedule since new. Please help me figure out problem, as dealer cannot figure it out.

Usually the caliper is at fault, but the brake hose on that side must now be changed.

What happens is the interior wall of the hose swells and the pressure from the master cylinder is enough to push the fluid through, but the retracting caliper does not have enough pressure to force the fluid back up.

Notice that they had some sort of problems with these hoses, probably a manufacturing defect.

Hi...
I drive an ML320, 2000 model. I was doing 80kmh on a main freeway in Melbourne Australia a couple of weeks back, and my front right brakes applied themselves while my foot was on the accelerator.. It pulled me to the right and stopped me within about 30m.. The car behind me swerved and just missed me. I just thank god it was a public holiday so not a lot of traffic.. I also am thankful a truck wasn't behind me..

I read this thread and went out and purchased a 2nd hand Yaw rate sensor for $300 delivered.. It took me 15 minutes to replace.. I also read they need to be calibrated so I took it down to my local Mercedes mechanic and he did it for free... He scanned my car and I was relieved to see the code C1120 N64 (ESP Yaw Rate sensor) Stored..
But I also had a code C1000 N47-5 (ESP,SPS,PML and BAS Control Unit) code Stored.. Its a ESP/BAS module that is black and sits under the washer fluid bottle. Ineed t get the part number (if anyone knows it that would be great) as I want to price a 2nd hand one..
Ive had oil leaks and power steering fluid leaks and the mechanic said I will need to replace that unit because some fluid may have got into it.
Im a bit sceptical as these two codes seem to have come up together.. I asked if the Yaw rate sensor failing could cause a fault code in the BAS module.. He said he doesn't think so.. I would think it absolutely could..
Anyway Im gonna drive it and see how it goes.. I've booked in to have all the leaks fixed and the fan belt replaced..
This problem should be recalled.. Its the most dangerous thing that's ever happened to me on the road and I'm very lucky to still be here... When you have no cars in front of you and your car just pulls up suddenly, the people behind you haven't got a lot of time to react.. Its like driving behind someone and they slam on their brakes for no reason..

I've fixed 3 other problems with my car since I've had it..
When I 1st bought it the BAS/ESP lights would come on and when ever i did a left hand turn at slow speeds, my front wheel would grab as I was turning.. That was a Lateral acceleration sensor.. It sits near the Yaw sensor under the centre console. Takes about 15 mins to replace and is a plug n play...

My car used to not get out of first gear sometimes, or it would stutter up the road.. I'd have to turn the engine off and restart it... That was the mass air flow sensor.. Another easy Plug n play fix..

The other was a Crank shaft sensor.. My car just stalled at the lights for no reason and wouldn't start.. That part is under the hood and easy to replace once you locate it.. About 10 mins work and another plug n play...

Lets hope the Yaw sensor fixes my problems as I plan on towing a boat in the next few weeks..

Thanks for the informative posts guys.. Its certainly saved me tonnes of money over the years..

To avoid confusing future readers of this thread, module N47-5 is the ESP/BAS control module, an electronic part inside the engine bay fuse/relay box. The black unit under the washer reservoir is the ABS pump, a hydraulic part.

Code C1000 usually means you need to replace the N47-5, not the part under the washer reservoir.

Welcome to the forum.

Cheers.. But just to clarify what my mercedes mechanic said...
He said that the ESP/BAS pump has a module on the front of it which needs replacing... That is what he said the N47-5 fault was.. He showed me what needs replacing and showed me it was under the water reservoir on the back of the ESP BAS pump..
From what I understood he said the relay "could" be the issue so to be safe he swapped it with my central locking relay to see if it keeps faulting.. But he is convinced i will need to replace the module on the front of the ESP/BAS pump with the code that came up...
Personally I dont think I will have to replace it.. I think that code came up when my Yaw sensor faulted...

I'd have to say that the explanation your mechanic gave you is incorrect. The electrical unit attached to the front of the ABS pump is commonly called the "solenoid pack" and has its own set of codes (ranging from C1300 to C1319 as shown in the attached pdf).

As none of these codes were set, it is unlikely that the solenoid pack (A7/3) is faulty.

When reading these tables, the right-hand column lists either the test needed or the part that requires replacement.

This linked page explains about the solenoid pack and how you can send it to the USA for repair for a flat fee of $100 + shipping. --> http://www.modulemaster.com/en/servi...des_motors.php

The problem you have described doesn't need a recall. It gave you the ESP/BAS warning light and stored the codes - these should have been properly read and the faults rectified in order to avoid the sudden braking incident you experienced.

Thats great thanks for your explanation... In your opinion, by replacing the Yaw sensor, that should fix the sudden braking problem? And could have that sensor fault also sent a fault code of n47-5 once the brakes had applied and the bas esp lights came on?

Ive located the module.. Its a big silver box behind the fuse box.. What fuses/relays are associated with this box??

The code C1000 doesnt show in that pdf file.. I think it starts at C1010 which describes what to do if the voltage is too high or too low..

Cheers.

(post deleted - quoted below)

I notice a lot of people refer to the solenoid pack as the BAS ESP module. Even the people who refurbish them call them a module. It makes it very confusing.. One mechanic on another site talks about the traction control unit and then says its under the water reservoir. BUt I take it thats the same unit you say is behind the Fuse box.
You are the only person that has said that the codes I got refer to the unit behind the Fuse/relay box. . So thanks for that. Saved me a lot of time and money buying a new solenoid pack .
Ive purchased the unit you said but wont replace it unless the codes show up again.. I got it for $130
This unit is out of the exact model and year (and even colour) as my car. Are they a plug and play or do they need to be programmed / calibrated?
Thanks in advance..

Just to clarify things.

From 1998-2002, the ESP/Traction Control Module is housed in the fuse/relay box.

From 2003 on, the same module is attached to the ABS Hydraulic unit.

Please UPDATE YOUR PROFILE in USER CP.

Technically the solenoid pack contains a control module (for the solenoid valves) and the unit is a traction control unit - a hydraulic one. So these terms are correct. It's probably better to specify the MB number to avoid ambiguity.

It's a complicated system, with several control units & modules. If you're interested in details, read this pdf --> http://www.mercedestechstore.com/pdf...2002-25-04.pdf

(Please stop quoting everything I write - it makes the thread twice as long. :))

Im tipping my mechanic thought he was looking at a later year car then or just got mixed up.. As when I rang him and said I purchased a module and that it was silver, he said the Module should have a yellow plug and was black.. He had pointed to the module attached to the pump when he showed me what needs replacing and he said I could do it.. It was just a plug and play.... Anyway, Its cleared it up for me so thanks to you both..
If the control module in the solenoid pack faulted, it would show codes from 1300+ from what DrX said.

I wont quote anymore and have updated my details.. :)

Cheers. :y

What is this reference to "yv"?

You've both... :y

Do us all a favor and spell things out.

I don't know why you wouldn't go ahead and replace your faulty N47-5, having already bought it. Do you need another random one-wheel braking episode to convince you it's bad?

It doesn't need programming. (but if I'm wrong, I'll be corrected)

If it's used it's a plug and play. But the codes in the donor module must be read and erased first.

MY friend has a 2000 ML320 and he experienced this problem twice. He took it to a regular mechanic who experienced the same issue (dangerous may I say) . He doesn;t know what the mechanic replaced but after that the problem went away. I would not call this a random problem when 2 or more are seeing it. It may be one of those buggy software behaviors when sensors/switches don't behave perfectly as expected when new as it happens in real life. This seems a good example of letting too many kids or people without relevant experience write software for complex machines such as cars.). Why would it be safe to apply brakes on all 4 wheels for whatever sensor failure issue?). The only plausible software programming I could see though would be for the assisted braking if the brake pedal switch were to fail and somehow tell the computer system that the driver must have pressed the brake pedal too fast possibly to avoid an accident or hit something. So just for the fact that the brake pedal position switch is cheap enough and easy to replace I would get that taken care of first. If the car is doing 55MPH and then suddenly the brakes are applied :word:hard I am sure lots of lights will come on the dash as sensors will indicate wheel lockup and even traction issues, so I believe that the lights that came on were more the results of the reaction to the switch failure, which was to "assist" the brake response by applying full braking autonomously. Now if this is a generic design issue with the brake pedal switch due to quality control or lack or redundancy verification it would be a totally different question with regards to quality/safety controls. Funny enough this would a kind of issue that may not even be logged as applying brakes hard by hitting the brake pedal fast is possibly something that is not recorded. I would think that anything that triggers the car to autonomously take an action should be logged, even if most of the time it is not due to a part fault.

Video of my ML on fire at the right front brake
 

https://www.youtube.com/watch?v=qgwb...ature=youtu.be

My right front brake just caught on fire after a 40 mile drive. I had new brakes (rotors and pads) put in by a Mercedes specialist less than 200 miles ago. I called them up and they think it is the yaw rate sensor. The car did not pull or make any sort of noise and no warning lights came on. I will update as I find more.

When this happens it is usually the brake caliper that freezes up.

I just got a 2000 ml320 called the company to get the code for radio they said theres a recall on the brakes any mercedes dealer will fix

my gauges stopped working after the ignition got stuck took out the tumbler filled down and the pins. does anyone know how to get the gauges to work.

Open a new thread. This is not a bazaar.

Welcome to the forum

ml 320 2002 braking on its on
 

Have an ml320, 2002, bought new, 213,000 miles. Car has braked on its own several times, Bas/Esp light comes on when this happens. Took it to a local shop, they ran the codes and replaced the brake light switch, however this did not fix the problem. Spoke to the mechanic, asked if hitting the ESP dash button at every start up would turn off this system, and prevent this from happening, he said yes. Unfortunately , even with the ESP turned off, and the triangle warning light on, while slowing down and braking a couple of times, the brakes assisted by applying hard and pulling hard, and then the Bas/Esp light came on, and the triangle warning disappeared. Have also noted that several times when driving, and not applying brakes, the triangle warning went off, and the Bas/Esp light came on .The car has never braked on its on when the Bas/Esp light was on, only when the triangle warning light was on, or when no light at all was on. Have read all the comments in this thread, and similar comments on other sites, and it seems that even MB dealers cannot always solve this problem . The yaw rate sensor seems to be the likely culprit, but I am hoping to be sure before I have this replaced. Does anyone know why hitting the ESP button, and supposedly turning the system off, why this could still happen, and also is there a way to permanently disable this system, so that the car can't ever self brake again?

Yes it is probably the Yaw Rate Sensor, but to make sure you will need a scanner that can read ABS code, namely C1120 Yaw Rate Sensor or C1142 Lateral Acceleration Sensor.

Thanks for the codes. If it is determined that the Yaw Rate Sensor is the cause of the self braking, can the Yaw Rate sensor be removed, not replaced, to stop this problem?

Absolutely not. It must be replaced or nothing will work.

codes were c1120( 5120) status: current
c1120 ESP Yaw Rate Sensor ( b45) ; signal cable open circuit/ short circuit, is the print out that I received.
Price to replace part $ 980, w/o a guarantee that it will fix the problem, so am mulling over my options.
Questions: 1) With the ESP button pushed off, why will it still self brake?
2) With the ESP button pushed off, after about 10 minutes of driving, the warning triangle stops, and The ESP/BAS simultaneously lights up. It has not self braked with the BAS/ESP light illuminated, does anyone understand the reasons for the self braking with the ESP button pushed, but not when the ESP/BAS light is on?

Resolve yourself to the fact that you have to replace the Yaw Rate Sensor and after replacing it the code/s must be cleared.

Your other option is to salvage a working used module from one of the growing collection of retired MLs in junkyards.

If you need a guarantee, you can have a dealer fit a new sensor. If that doesn't fix it, they can put your old one back in and you don't have to pay for the new one they tried.

The car doesn't brake by itself if ESP is switched off, but I suppose the Brake Assist System is still operable.

Could not find a used sensor in my area, had a new one installed, driven 50 miles w/o problem , hoping that this solves it.
Re Having ESP switched off, when I hit the brakes , sometimes it would "assist" rapidly, so the brake assist was still "working" in these cases, but it did not brake on its on with ESP switched off.

Similar
 

I have a 2002 ml320 that when I am stopped and turn left the break grinds ( sounds like ABS) but it only does it at 2 to 7 mph. It only happens on the left front wheel and only turning left. I get ABS lights every once in a blue moon when it drags hard. If I press the ESP Off button it makes no difference whats so ever. Do you guys think this is the same issue or a different issue all together.


Thanks in advance.

That's not an ABS issue. Have you taken the L/F wheel off to investigate?

I have removed the wheel and inspected the calipers, brakes, cv joints and don't see anything out of the norm

You must make sure that the backing plate is not rubbing up against the lower rear of the rotor.

Ok I will check this tonight after work. But it feels like the brake is beefing applied on it. Sometimes the car has problems getting going turning left like the break is applied.

Thanks again

Sorry just now getting back after tearing more into it. There is no rubbing anywhere on anything. So yesterday I swapped out the caliper and the brake line with same results. The other night going through a drive through and all 3 and lights came on and stayed on till next morning then just went away. I am at a loss on trying to figure this out. Just not making any sense to me.

Thanks again.

Have the codes red. It could be the YAW sensor.

Hello,
We have a 2001 ML320 w/ 170k miles. Last night I had the same thing happen that original poster described with the exception of the brakes being applied (or at least it didn't feel like they were applied)

pulled out of driveway and started accelerating, hit approx 35 MPH and the yellow triangle with ! started flashing and could not accelerate any faster. Felt like the gas pedal hit a flat spot or there was a governor on the engine. While limping it to
our mechanic and stopped in traffic the triangle went out and the ABS/EPS lights came on. Once traffic started moving the vehicle excelled up to road speed and you could drive 50/55 mph no issues (maybe faster but that was the posted speed limit)

Mechanic put it on the scanner and it showed no engine/transmission codes but had a brake code and he suggested we try and replace the brake light switch which I've seen has been mentioned and tried in this thread (but doesn't sound like the culprit )

Was too late last night to get the part and we were going to shoot for Monday. He reset the code and the lights went out, on the way home it started again with the triangle flashing and the car not going over 35 mph. I decided to try to put it in neutral and rev the engine and that seemed normal, the engine would Rev up to 4/5000 RPMs, However when it was in gear it would not go above 1-1500 RPMs and only 35 mph (unless held to the mat, added additional info about RPM's in next post). While in neutral the car coasted fine so it didn't feel like the brakes were on at all. Not sure if this is the same issue as the original poster but it sure sounds like the same issue minus the braking

Does anyone suspect it could also be the capital YAW sensor, or is this some type of separate issue?
Thanks in advance

And what was the brake code? It has to be a Cxxxx?

Um, That I didn't ask him. But I can find out

Also another thing I forgot to mention in my first post,
I tried pushing the accelerator all the way hard to the floor, the RPM's would go to 3-3,500 but the speed would NOT increase. If I let off and coasted, the vehicle would get under 35 MPH the triangle would go out and you could then accelerate back up to 35 but no higher and again the flashing triangle,,,,,,,,,,,,,,,,,

Thank You

YAW and Lateral sensor
 

If you are having BAS/ESP problems and think it might be one of these sensors, consider if you have had a recent spill in the shifter area. The sensors are underneath on my '04 ML350. I spilled a little coffee in this area and the BAS/ESP lit up for a couple of days. Before spending hundreds on a sensor, it might be worth popping the shifter and cleaning and drying the sensors and all wiring harnesses/connections.

very possible. It's our sons car. So it's hard to tell with him but I'll ask :D

Nope nothing spilled in there.

After work yesterday I took it for a spin. 35 MPH same deal. Flashing triangle and no more speed or throttle. Pulled over, turned vehicle off, restarted and it drove fine. Drove it for 15 minutes no issue's , no warning lights.
He heads back to college 3 hours away at the end of the week and not sure how to proceed now .................

.
 

Your vehicle has detected traction loss and thinks it is about to spin off the road. First you need to get the brake code the vehicle is throwing.

testing yaw rate sensor
 

why not recommend that the OP tests the yaw rate sensor himself first instead of spending some place between $500-$1000 for a new sensor and not being 100% certain the problem he mentioned was actually caused by the yaw sensor? there are quite a few easy ways to test the yaw sensor... here's one testing technique which came up first:

https://sciencesphere.blog/testing-the-yaw-rate-sensor/

I've just disabled all the electronics I can and now the car runs much better on road without ABS ESP ETS BAS etc., etc.!
No Mercedes-Benz Super Nanny = much more fun car!

disabled how? by pressing the ESP button on the console?