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.