Hi, new member here! Also don't know a lot of tech-speak so please forgive me. In my 2017 GLC 300 4MATIC, I was driving around listening to music via bluetooth a few weeks ago and out of nowhere my COMAND screen said "COMAND Shutting Down", and about 4-5 seconds later, blank screen, no audio. I pressed the power button on center console and the mercedes logo came up, audio came back on, and then again, "COMAND Shutting Down", and then it shut down again. I noticed later after turning car off then turning car back on, that if I immediately put car into reverse, the rear cam would turn on and stay on for as long as I was reversing, though COMAND shutting down would still happen.

Things my husband has tried from various internet searches

1. removing some fuse (not sure which one) and waiting for a while then putting fuse back in (nothing)
2. Replaced main battery (nothing)
3. reset by holding the eject disc for 10 seconds - can see and hear a reset, but still same message COMAND shutting down after it powers back up, (so still nothing)
4. removing plug to satellite radio under floorboard in rear cargo area (THIS WORKED BY KEEPING COMAND SYSTEM SCREEN ON *BUT* NO AUDIO whatsoever - tried radio, bluetooth, making a call, etc and no audio.
   • It's worth noting that trying to save any audio preferences e.g. surround sound to on vs off does not save. Also dash not dimming with scrolly-wheel near headlight settings either.

Also worth noting that before we tried #4, we took to dealership and they were able to replicate the issue (obviously) and said they would need to "conduct extensive diagnosis for Comand issue-performed short test and found that tuner control unit, sound amp, and head unit are not communicating. Fuses for all components are good. Will require disassembly of vehicle to access individual components to test for issue" which would have cost an additional $753.52 beyond the initial $200 diagnostic charge we paid them to do.

HELP?!

Comand works but keep shutting down.So now what is your objectives: you want to fix it yourself or have the dealer take care of it?

It may be an easy fix but not simple to figure out or it may be a $2500 unit plus 2Hrs of labor.

Changing the battery was a good call because it could well be a low-voltage "consumers Off" protection.

> Make sure the cabin filter is either newish or removed to allow good air flow to circulate through Comand and Display.
These are heat generating units that rely on inner dash venting. Filter Access located in passenger footwell. Easy hack with YouTube search skills.

I don't suppose you care to learn "ODBC Scanning" skills for the next step ??

Thanks for the tips! I am going to try removing/replacing the cabin filter next. I have a cheap diagnostic scanner but am pretty green with using it - tbh I am all ears if you have any advice reading the scanner.

I realize this may end up going back to the dealer for a pricey fix, but I have to admit I was really hoping from their initial diag test, it would have turned out to be some sort of system software update. Instead, I quickly got cold feet when I received the quote from the dealership, especially with such limited communication between myself and the tech (have to go through middleman in office). This is likely because I do in fact have a local mechanic who I truly trust and has done the regular maintenance and even repairs to my last 4 cars including two mercedes ranging from minor issues with the MB's to electrical issues in an old jeep. Luckily he treats me extremely fair on diagnostic stuff, so my gut instinct was to have him see if he can work any magic - he said to swing it by his shop tomorrow morning. If not, I'll be slowly (and quietly, aside from my crying) driving back to the dealer

And yes, admittedly I am a fan of DIY where at all possible (ha!). So today, i'll try the cabin filter thing. And any ODBC scanning skillz you can offer! THANK YOU

Go ahead and try things mentioned above then let your Indy get a stab at it if he specialized in Benz.

The audio system involved here is not trivial, it runs a "MOST Network", a fine German creation. The head unit is not easily serviceable either...

So before you realize, you could find yourself in deep-waters -or perhaps not if you're lucky.

Get a $150 iCarsoft or Autel scanner on Amazon prime to see what it says. If not 100% useful now, it will be next time for sure to give you heads-up.

Scanner are a bit like a MD stethoscope: you don't become a heart surgeon just with the tool alone. Youtube + practice + forum search!!!

Knowing what fault code is active tends to keep the Sce Advisor confusing games dialed down a notch.

I had some weird things happening in my 2013 GLK caused by the auxilliary battery. Command would shut off too quickly, the warning indicator in the right hand mirror kept going off, collision sensors going crazy, ECO Stop no longer working (noticed was using more fuel due to waiting at stop lights). Finally got a display indicating "Auxilliary battery malfunction". Its a sealed battery under a cover where my spare tire goes. Seems they can cause a heap of trouble before you get an indictation of what it is. Replaced mine, and poof! all fixed. I bought from Mercedes, but I'm sure a good battery shop could sell you the same type of sealed gel cell with a vent that connects to the vent tube for a lot less. Wonder if that could be it? It's an extremely simple replacement, just make sure the wires don't touch the car body (masking tape), and ensure to reconnect with the right polarity.

Hope that helps!

I thought I'd provide an update on my issue with Command shutting down. I took the car into an independent MB certified mechanic, and after testing, it needed a new infotainment display control module. This ended up being a $3,400 repair ::weeps:: but the turnaround was quick at 5 days.

MAY YOU PLEASE PROVIDE ME DETAILS OF THE infotainment display control module YOU PURCHASED THAT NEEDED TO BE REPLACED I AM TAKING MY CAR TO THE PRIVATE MERCEDES MECHANIC AND HE IS WILLING TO LET ME FIND THE PART AND HE WILL CHARGE ME LABOR TO JUST HELP ME OUT WITH ALL OF THIS.
ANY DETAILS OR MORE EXACT DESCRIPTION WOULD HELP.

THANK YOU!!

Here is my exact invoice. So far, all has been perfect since replacement. They guarantee work for 3 years.