Ok, so i have gone through just about everything troubleshooting this Comand issue.
The car is GL450 cdi -07 x164.
The problem is the comand turns on from the button, show mercedes logo. Then turns off by itself after about 10-20 seconds.
Sometimes it can very seldom turn on by itself and work (radio on and sound works) for maybe 1-2 minutes then turn off again.
Now at first i tried all the reset procedures but none work. Then i bought a bypass adapter for the MOST bus to test if some component of the system is not working and thus making the comand not work.
But bypassing all other components didnt make the comand work. And it seems fiber optics red light is going through the system full loop (starting from comand/agw and ending to cd changer, well comand again).
One thing that is strange to me that i cannot connect to comand unit with star diagnosis through the audio menu. I tested the can bus lines from the unit is connected to the body can split on the car (both high and low).
So right now i conclude that the comand unit is faulty.. Are there any other ways i can test the unit before buying a new one? Just want to make sure before paying big money for it.. :/
Or anything else i can test? Any ways to bench test comand?
Thanks for any help..

 

Did you read through the whole post? I have star diagnosis unit and i have tested using das Xentry but the audio control unit cannot be connected to at all.

 

I have the same problem. I figures out a workaround to make it work. I hit the ON/OFF button repeatedly till the system boots up after 10 seconds. It then runs fine till the next time I start the car. Hope this works for you.

BTW, where did you buy the fiber optic bypass loop. The ones they are selling on eBay/Amazon are not the correct type for the Mercedes.

 

Ok, thanks for the hint but doesn't help for me anymore. I did buy the comand-unit and that fixed the problem for me.
I did buy the loop adapter from ebay, and it did work on mercedes. The same as here for example: https://www.ebay.com/itm/Fiber-MOST-...9XBfD2&vxp=mtr

 

Check out the fiber optic bypass loop this guy uses on his S550. It looks nothing like the one being sold on eBay. Your thoughts?

 

Yes, that one sure looks a bit different. But for me, the one sold on ebay did fit, the car i was working on is Mercedes GL 420 CDI, -07.
It is Euro model car, maybe the connector is different? Or year model difference?