Suddenly started getting a Brake EBD, ABS, and ESC Inoperative message on the dash. Starting up, everything's fine, until I hit about 10mph. The cruise control is also inoperative.

I have seen a LOT of similar posts, some involving power steering (not a problem with mine).

There are no error codes, and the problem "fixes itself" every time I turn the car off (until I hit 10mph again).

Many of the issues online seemed to be related to a bad wheel speed sensor, so I monitored those while driving. They all seem to agree, but then randomly all go to "speeds" in the minus 600 range (probably simultaneously, but the refresh rate on my Autophix scanner probably makes it look otherwise).

I did a short video showing the error popping up, as well as the wheel speed sensor anomaly.


Some commonly reported "fixes" from the MANY online threads...

Brake switch (the reported position on my scan tool seems to track OK. But is it normal for an X204 to be able to start and shift out of park without my foot on the brake?)
Wheel speed sensor (all seem to be reading the same, other than the -600 reading thing)
Various modules (hope not....)
Battery (reading mid-14 volt range running, and good voltage when not running)

Quick fixes I've seen (and will probably try):
1) Cycle steering from lock to lock and back to center
2) Apply parking brake and release several times
3) Remove and clean the brake switch (easy enough). If that doesn't work, replace it.
4) Ask the kind folks on mbworld.org to help... ;-)

 

Update... (I know you're all breathless in anticipation). ;-)

Tried cycling the steering. No joy.
Tried applying / releasing the parking brake. Nada...
Tried hitting the "OK" button as the car went from just under to just over the threshold speed (read about someone having luck with that). No difference.
Just for giggles, I tried getting up to 20mph, and coasting in N, turning the car off and on, until it was under the threshold speed. Didn't seem to do anything, but when I restarted the car after stopping (immediately), the error didn't come back. I checked, and the wheel speed sensors are still doing that odd thing (going from actual speed to -6XX, just like in the video).

I drove around the neighborhood for a couple miles, and the issue never came back.

Anyone ever have this issue and have anything to add that might point toward the actual source of the problem (I'm not remotely convinced that it's really "fixed")?

 

Might check this thread ... fixed at Post 13.

https://mbworld.org/forums/c-class-w...e-message.html

 

Thanks - I'd seen that thread (and dozens of others). Thing is, all of the wheel speed sensors are acting the same (at least on the scan tool).

The more I think about it, the more I suspect the brake switch. I'd just assumed that Mercedes didn't require a foot on the brake to start the car or to shift out of Park... but I'm guessing that you DO have to push the brake pedal to do either (leading me to suspect the brake switch is cooked)...

 

Hmmm. I just went out to our 2014 GLK Base, and it fired right up without the brake pedal depressed.

However, I think most all fairly modern vehicles require the brake, to shift from P To D/R/N.

Our 2001 Wrangler requires it, the 2001 E320 requires it. Heck, the 2019 Ferris zero turn mower requires it

 

I looked up the owner's manual, and it says that the brake pedal has to be pushed to start the car or to shift out of Park. Thankfully, my 1996 Jeep (manual transmission) doesn't. ;-)

I just ordered a replacement switch from Rockauto (under $12 delivered). Seems like a fairly high-probability move. At least it's an easy job (probably three minutes start-to-finish).

 

You did that on purpose so I'd read our manual (page 101).

Yes, if you use Keyless-Go, you have to press the brake.

If you only have SmartKey, no brake required to start.

 

Thanks - it's good to know that I won't be losing all of the self-determination features of the car with a new brake switch (I don't have Keyless-Go).

 

My manual says this:

o It is only possible to shift the transmission
from position P to the desired position if
you depress the brake pedal. Only then is
the parking lock released. If you do not
depress the brake pedal, you can move the
DIRECT SELECT lever but the parking lock
remains engaged.

I never paid much attention, but I'm pretty sure that is how it works. Same with the GLS, too.
(Or is everyone else saying the same thing?)

 

... I think that's related to moving the gear stock to, let's say, to Neutral because you're having the vehicle towed.

Here's the "starting the vehicle" page - it's from a downloaded PDF version from MB. My GLK manual doesn't show "for diesel..." because it's a plain Jane Base model.

 

Has the reluctor ring been brought up yet? A search might be in order, to see if you're having similar symptoms.

 

I don't suspect the rings, as all four wheels are reporting the same kind of thing. I'm thinking it MAY just be an anomaly with my Autophix 7770 reader. I'll check it again after swapping out the brake switch to see if it's behaving any differently. If it's not setting any errors AND still oscillates between actual speed and the minus 600 range (on all four wheels) I'll just ignore it... ;-)

 

Strange thing - while I'm waiting for that brake switch to arrive, the problem just went away. I've been driving for a few days without any recurrence. I suppose I'll just wait for it to act up again to swap out the brake switch, just so I'll know if that was the issue or not. What's really funny is that the problem went away when I was double-checking that I could shift out of Park with my foot off the brake, and found I couldn't, and then immediately noticed that the problem wasn't occurring. I think that all points to a problem with the brake switch, but would really like to make sure.

 

On our 2014 GLK Base, I've noticed some "hesitation" from the moment I pull the brake release handle until the "brake" light on dash is extinguished. (I always use the parking brake at home in garage).

Rarely (but mostly only in the wintertime[1] ), I have to put my left foot UNDER the mechanical emergency brake pedal and "lift up" the pedal when I pull up on the emerg handle, to "assist" it to return to it's default resting position.

Apparently , the "return spring" (or whatever is used) to bring the emerg brake back to its proper resting place is weak (for ours).


[1] I'm in south-central Texas, so Winter only lasts 2-3 months, if that long (maybe 1-2).

 

My emergency brake has the same "sticky issue". Once in a while (every 10-20 drives) it'll report that the e-brake is on. It just takes a tug on the release to get it resolved, but I have, like you, had to hook a toe under the pedal to lift it a bit. I suppose it's probably a misadjusted microswitch, but honestly haven't gotten to the point where it's enough of a nuisance to get me twisted up under my dash to look for it. ;-)

And FWIW, out winter here in Arizona is shorter than yours! ;-)

 

Winter? I think we had one here a few years ago. Hard to remember.

 

@Odd Piggy spent most of my early years deep in your town (native), but moved more north (Magnolia area) in these later years. Big city turmoil is non-existent here.
.
​​​​@habbyguy ... anything new on this issue? Has it shown up again, or did you replace the brake switch?

 

The problem hasn't occurred again since it "self-healed". I've got the brake switch in hand, and will just wait for a future failure before replacing it. I guess that'll mean keeping the switch in the glove box in case it happens on a road trip... the good thing is that replacing the switch is about as easy a job as you're ever going to do on any car.

 

Sigh... time for a "13 month update".

The problem had gone away, and stayed away until a week or so ago.

I'd read that the problem could be associated with an electrical gremlin, and my alternator was getting flaky (not charging at low engine RPMs) so I swapped it out thinking it might help this problem, too... Nope.

I'd ordered a brake "switch" last time, but the problem went away before I could swap it out. I put in the new one - no change.

And since one of the possible issues would be the wheel speed sensors, I thought it likely that my recent CV boot leak (followed by a replacement of the boot) could have gotten some metal-rich grease on the sensor, I took the sensor out, cleaned it, and used compressed air to displace any latent grease from the CV boot leak (though of course, I'd thoroughly cleaned the CV axle rotating surfaces). The problem came back as soon as I drove the car the first time (and exceeded the 10mph "trigger speed").

However, driving around the neighborhood looking for clues - the problem once again seemed to disappear. I made an updated video showing these steps (just as an FYI - you don't need to watch it if you read this post). ;-)

Funny thing is - the problem then DID crop up again. I shut the car off at a stoplight and restarted it, and whadayaknow? It didn't come back.

Color me perplexed, but I can only hope that the problem stays away for a good long while (hate to lose my cruise control on one of my epic 7-8,000 mile road trips!!!).

FWIW, here's the "update video"...

 

I've driven around (in an empty parking lot!) for a while, looking at the output from all four speed sensors. As before, they transition back and forth from what looks to be an actual speed (all four agreeing) to -600-something kph. But none seem to act different from any others.

The one saving grace is that I can fool the system by accelerating to well over the 10mph trigger speed, shift to neutral, then turn the engine on and off a couple times. Often, the error will disappear, and won't reappear until I restart the car (and maybe not then, at least not every time).

I also noticed that my Autophix scanner didn't seem to be able to communicate with the ESP system, other than to display the real-time data (such as module voltage and wheel speed sensor output speed). I'm not sure if that's normal, or indicative of an issue with the / a module...

 

OK folks - I have continued to try to chase down this odd, intermittent (and annoying!) problem. I think I fixed it!

I monitored the wheel speed sensors and had not seen any differences between any of them, and I replaced the (cheap and easy to swap) brake switch without fixing the now nearly constant error message, and then disconnected the battery for a couple hours. I was ready to move on to another option. Other than (supposedly) shutting down the ABS and stability enhancing systems (which I'd probably never notice until an emergency situation) the real inconvenience is that the cruise control won't work when the error message is showing (and when you do regular 7-8,000 mile road trips, that's an issue).

Today, I decided to check the ground connections to the ABS module (all looked fine), and then decided to remove and clean the connector to the ABS module itself (that's the one that's connected directly to the ABS pump / distribution block). It was clear that the area had been exposed to dirty water, based on the "bathtub ring" around the connector edge. That's where the fun started...

The first thing that happened was the lever that's supposed to gently pry the connector off didn't move anything, and broke internally with only moderate pressure applied. I ended up lubricating the "slides" and gently raising them incrementally while prying the connector loose. Finally got it off.

I cleaned the connector (male and female sides) with electronics cleaner, and then carefully reseated the connector (push the connector in, push down each slide, push connector in again, rinse and repeat).

When I started the car after putting it back together I immediately got the "Brake - EDB, ABS, and ESC inoperative" message - prior to this, it only popped up after a restart when I hit 10mph / 15kph. Running up to "speed" (in this case, about 30mph) didn't clear anything, so I used my hack of putting the car in neutral, and turning the key to position one (full left, without locking the steering!) then on (without engaging the starter) and back a couple times, all while coasting from about 30mph to about 20mph. Then I restarted the engine (I'm in neutral) and the error code disappeared immediately. And better, it didn't come back after about a dozen stop / restart / drive to 20mph opportunities.

Now I know that this gremlin has been really intermittent and flaky, and I know it's always possible it will return, but for now I'm cautiously optimistic that I've finally found and fixed the root issue. I may never know exactly what it was inside that connector / connection that caused the problem, but it might have been nothing more than a stray droplet of dirty water providing a high-resistance "short" between a couple pins on the connector.

And of course, I did a video of the process - this appears to be a more common problem than I suspected, based on the number of views my previous videos on the subject received. I hope this will help some others in the future (whether they drive a GLK or a W204 or similar sedan).

 

Well THAT celebration was short-lived! ;-) The "fix" held for a while, then the symptom came back (appearing, as always, as the car hits 10mph).

I deleted the "fix video" though I may re-craft it to show another step in the diagnosis process later.

Strangely, I just noticed that my previous posting doesn't have the "edit" option (so I could remove the video "carcass").

 

There's a time limit, to reduce the instances of revisionist history...

 

I was able to do some more troubleshooting today. Hooking up my Autophix scan tool, I saw the same issues I'd seen prior, but never been able to definitively ascribe them to the scan tool or the car... until now, that is...

I was able to put my hands on the GLK formally known as "my project car", and hook the same scan tool up to it.

My GLK (2011 GLK 350 4Matic)
Wheel speed sensors all toggle between actual speed and -600-something kph, randomly (the speeds all seem to agree when they're reading "reality".
I can't read faults, or clear faults on the ESP system, but get a "failure to communicate" error with the system
I can read all the "live datastream" items related to the ESP system.

Project GLK (2012 GLK 350 RWD)
Wheel speed sensors all read actual speed, all the time (and agree)
I can read faults and clear faults on the ESP system (though there were none)
I can read the live datastream

I'm consistently able to do my "hack reset" on the ESP/ABS fault by accelerating to 20-30mph, shifting to Neutral, turning the key to position 1 (engine off), then back to run a couple times, then restarting the engine. Doesn't work every time, but probably 2 out of 3. Once I do that< I can drive hundreds of miles with no errors, including stop-and-go (not turning engine off). Once I turn the engine off, I almost always get the error when I hit 10mph, though even that is hit-and-miss.

I'm a bit (!) perplexed by all this, and suspect that I do have a flaky module (ABS?). Is there an "ESP module" or is that functionality contained in the ABS module? I see used ESP modules but haven't found out quite where they live yet...

Does any of this ring any bells with anyone out there?

 

Another update on the never-ending saga. The error has been pretty much 100% consistent for the last few weeks, and I resorted to pulling out the BIG guns... I bought a Launch X431 Pro S bi-directional scan tool to enable both digging down deeply into the system to see if I can discern any more details, and (more importantly) it will allow reprogramming a replacement ABS / ESP module (happily, this can be done without requiring me to drain or bleed the brake system - the electronics of the module can be removed from the ABS pump block without opening anything containing brake fluid.

I put a few thousand miles on the car in this last period, always resetting the error by putting the car in neutral, then turning the key to the #1 position a couple times, then re-starting it, all while coasting at over 10mph. That allowed me to continue to use the cruise control, most importantly (though it also reset all the delightful orange lights on the dash).

So now I'm finally back and ready to dig into the problem, and .... yep, the problem just went away. I've put another 5-600 miles on the car without a recurrence.

My guess is that there is something intermittent on the ABS module. I've read accounts of cold / fractured solder joints and PC board runners and suspect that's likely the issue. Of course, pulling the module and scraping all the conformal coating off the PC board and resoldering anything that doesn't look right sounds like something I should try when I won't be needing the car for a few days. Or perhaps I'll just keep my eyes open for a reasonably-priced numbers-matching ABS / ESP module and swap it in...

Stay tuned to this channel... ;-)