Hello.

We just purchased a beautiful 2012 GL550 for my wife.

She is truly in love with this vehicle. We've been together for 39 years and this is the first time I've seen her so excited about any vehicle she's owned.

There is a problem that has us, our local independent mechanic, and our local MB dealer stumped.

I have searched and searched for any info on this issue and I have come up empty handed.

Here is the problem:

The car will suddenly brake after going about 3-4 feet on an incline.

This happens when going from park to drive (or from park to reverse if we are backing up an incline). It brakes for about one second.

It's as if one were starting to accelerate and then after a few feet one were to quickly tap the brake pedal.

Here is the sequence of events:

1) The car is in PARK with the parking brake ON.

2) Start the engine.

3) Place foot on brake pedal and release the parking brake.

4) Press the accelerator pedal and start to go up an incline.

5) The car will go about 3 to 4 feet and then the brakes suddenly engage for a moment.

6) After that brief moment (about one second) the brakes release and we can proceed without further problems.

This only happens on inclines (and of course we live on a hill with a steep driveway).

It usually only happens when we are going from PARK to DRIVE (or PARK to REVERSE if we are backing up) on an incline.

Again, this happens when going from park to drive (going up an inline) or park to reverse (if backing up an incline).

This issue can happen while driving, but it is rare. Sometimes when we are stopped, on an incline, and the car has remained in drive it will do this. If we have to sit for say 30 seconds or more at a stop on a hill, when we accelerate the car will do the same thing: suddenly brake once we've gone about 3-4 feet.

My guess is a problem with Hill Assist?

I think it is using info from the potentiometer(s), or it would happen on flat surfaces.

The specifics on the vehicle: 83K miles. Mint condition.

When we bought the car it had a bad right rear wheel speed sensor, which we had replaced by a local independent mechanic.

There are not any dash warning lights on.

When our local mechanic and the MB dealer tested the vehicle they can duplicate the problem, but they cannot find any issues with their scanning equipment. Nothing at all. Everything checks out fine.

So, here we are.

We honestly do not know what to do.

Neither the dealership nor our independent mechanic have ever heard of this problem.

Our local MB dealer says that they will contact Mercedes Benz directly and see if they can help. We are waiting for an answer at this time.

I will happily buy anyone a beer (or case of beer, or even a keg!) if they can help.

Thanks in advance for your help everyone.

Sincerely Stewart and Christine.

p.s. I am sorry for the long post but I want to give you the best description we can.

 

When you test drove the GL before you purchased it, was the problem in existence?

I ask because it could possibly be the beginning of wheel sensors going out.

I have 2010 GL550 and had to replace mine at around 90k.

 

Did the issue only start after this sensor was replaced?

 

Hi Guys,

This issue was going on when we bought the car.

We bought the car out of state. It was a 6 hour drive to get there. We rented a car on the way there and drove the GL home.

During the test drive this did not happen, nor were there any ABS lights on.

We didn't encounter any hills or steep inclines on the test drive. There weren't any in the area.

Once we were heading home the ABS light came on after just a few miles and the cruise control stopped working.

We called the guy who said that this issue had never happened to him (yeah right) and that he would pay for a wheel speed sensor.

Anyway, we brought the car to our mechanic when we got home who changed out the right rear ABS sensor with an aftermarket part.

This did fix the ABS light and the cruise control (which I understand gets it's info from the wheel speed sensors.)

So here we are.

I did find an old post somewhere where somebody had a sort of similar problem. An MB mechanic had a customer who had a car where the sensors all tested fine. The car had an aftermarket sensor on it. They tried replacing the aftermarket sensor with a used OEM sensor that they had on hand and and the problem was solved. I've no idea if this would work.

We're taking the car to our local MB dealer today. Hopefully they can find the problem.

I sure learned my lesson about unscrupulous people out there.

I talked to the guy for over a week before I bought the car.

I'll never ever buy a car without taking it for an inspection again.

I will post what the dealer says today.

Thanks again guys.

 

Go with a MB wheel speed sensor only. The none OE versions can be iffy. If the MB wheel speed sensor does not fix, your wheel bearing needs to be replaced.

 

There was no real progress on the car yesterday.

Today the shop foreman is supposed to be in to take another look at it.

My wife was told that the dealer did send a message to MB directly and that they did not get a reply.

Hopefully we hear something today.

Thanks again for your help everybody.

 

Most likely wheel speed sensors but
only a MB Star code read will tell you that.
failing wheel speed sensors will cause a multitude of problems such as ESP and ABS failure, heavy steering and maybe the hill start acting weird.

have the car read out at a dealer or good Indy.
get a PPI next time especially when driving 6+hrs to go see it.

 

Hi.

Yeah, definitely a PPI. Learned my lesson.

Got the car back from the dealership yesterday.
We had it in for an airbag recall and a new battery as well.

They cannot find a reason why this is happening.

I did tell them about all of the suggestions regarding the wheel speed sensors.
They assure that they have all of the latest equipment offered and that everything checks out okay.

We're told that they made and sent a video of this issue directly to MB at MB's request.

I hope that MB can come up with any ideas.


My independent mechanic is very good. He services my Jaguar.
He has experience and certifications from working at both Mercedes dealerships and Jaguar dealerships.
His favorite brand is MB. He knows them well. Unfortunately he is also stumped.
I don't know if his diagnostic equipment is as good as what the dealership has.

In the meantime we will wait for the dealership to contact us.

Thank you for your help.

 

I fixed this issue today.

I purchased an inexpensive aftermarket set of aftermarket wheel speed sensors on eBay.

I paid $32.00 shipped for a set of all four, so I thought "Why not try it?"

Well, it worked!!!!

This solved the problem that even the local MB dealer could not solve. The dealer even contacted MB directly. They sent a description AND a video. The dealership never got a reply from MB.

The dealer service dept insisted that all of the sensors were good, even when I mentioned the advise given to me here on this forum.

I have no idea how long these cheap aftermarket sensors will work, and I don't care.

I will replace them all when one fails. I will replace them with OEM MB parts.

From now on I will replace them as a set instead of just one.

Thanks everyone for your input.

Stewart

 

Hi SWB, glad you were able to solve this issue. I have a similar issue that also happens only on an incline like my driveway on my GL450. When I let go of my brake pedal, and press on the accelerator, it slowly releases the brake pedal and all of a sudden the car lurches forward as if I was hit in the back (or as you say, a sudden brake for a second). My question to you is, have you noticed at that time if the brake pedal slowly releases or does it quickly release when this was happening. My brake pedal slowly goes back up (not the normal brake pedal release) like some sort of hesitation. Then when i press the on the accelerator, thats when I feel a sudden jerk or sudden brake then i can proceed to drive with no problems. Only happens when on an incline/slope. Looking forward to replacing all 4 speed sensors. Hope my issue is similar to yours and replacing the speed sensors will solve it. Thanks!

 

My GL550 does this too. Only from park to driver, or park to reverse, always on an incline. To me, it felt like the car was starting off in second gear and downshifting to first. If I put it in drive and then use the steering wheel paddles to put it into first gear, and tap the shifter back to drive and proceed to pull away it doesn't happen.

 

Try putting your transmission in sport mode instead of comfort. Comfort mode uses the 2nd gear to start by default (and a second gear for reverse).

 

default start gear is 2 in any x164. 2nd reverse gear is usually locked out (unless you set VMax reverse speed limiter to higher than 30 km/h in DAS developer mode.)

sport / comfort button doesn’t change anything in the tranny, only the shock firmness in the transmission for ADS equipped x164

some 7g in the car platforms also have agile mode, in addition to sport/comfort.

 

Hm, I guess you're right. Rather strange thing to omit in a 5500 lbs SUV. Especially since it is the top SUV.

 

W251 R-class has it and the same transmission but according to MB that is a car and nicht einen SUV oder minivän!

 

I'm surprised there is no sport or comfort mode like the S class has. First gear in the 164 is virtually useless unless you use it manually. How annoying.

 

The way go get the x164 to start in 1st is to select off-road mode, and then you’ll see how useless that gear is.

 

Hi there, just wondering did your car fixed after replacing all 4 sensors. My gl320 have the exact same problem.

thanks

 

Yes. That was the root cause.