Why can't I get sound from my Subwoofer in W220 Mercedes?

Question edited for clarity.
Question moved to model category.

Mercedes are the only manufacturer to have 8 or 10 fuse boxes :>D Don't forget the radio is also connected and monitored by the BCM.

Mercedes-Benz CL-Class & S-Class (C215, W220

Fuse Box Diagrams https://fuse-box.info > mercedes-benz > mercedes-ben...

Here you will find fuse box diagrams of Mercedes-Benz CL500, CL600, CL55, CL63, CL65, S280, S320, S350, S400, S430, S500, S600, S55, S65 (1999, 2000, 2001 ...

Mercedes-Benz E-Class (W211; 2003-2009) fuses ...

Fuse Box Diagrams https://fuse-box.info > mercedes-benz > mercedes-ben...

Here you will find fuse box diagrams of Mercedes-Benz E200, E220, E230, E240, E270, E280, E300, E320, E350, E400, E420, E500, E550, E55, E63 2003, 2004, 2005, ...

Fuse box diagram Mercedes w220 and relay with ...

FuseAndRelay.com https://fuseandrelay.com > mercedes
In our article you will find a description of the fuses and relays Mercedes 220 with box diagrams, photo examples and their locations. We will note the ...

‎Engine compartment · ‎Box on the left side · ‎Box on the right side · ‎Additional box

https://fuse-box.info/mercedes-benz/mercedes-benz-cl-class-s-class-c215-w220-1999-2006-fuses-and-relay

All the models

https://fuse-box.info/mercedes-benz

You need a skilled auto-electrician, not a mechanic, one that has a high end scan tool computer that can analyze the stored and live data, plus reading any DTC Codes.

To me, it sound like you have a failing battery, possibly erratic charging and some bad grounds. The electronics on Mercedes are overly complex.

Sounds like you have a case of "stuck shocks". There is such thing and they have to either be driven over a speed bump or something similar to see if they will come down. I'm sure they are riding very "stiff" and uncomfortable. If that doesn't do it, they will then need replacing. I hope this gets you straightened out, John 3:16-17 (KJV)

Here's a site that might help. Not exact for your model, but maybe enough to nudge you in the right direction. And demonstrate just how complex this system is....

Originally in German (of course), Google is translating it.


Google Translate

Original:
OLDTIMER Tipps fr Mercedes SL55AMG

In the fuse box under the hood, fuses 3, 6, 7, 10, and 12 are all directly related to the sound system. In the trunk, fuses 3, 6, and 7 are also directly related to the sound system. Please check all the fuse.

And also unplug the CD changer's power and fiber cable and then recheck the radio.

hello,good day,yes your may check the power supply and contact,if not corrected,send your car to a dealer for proper diagnose,maybe erase fault or configuration of your system is needed,to correct the problem,ty

Here you find all parts, page is on W124, to select W220 use the bar at the left.
If you want a listed part list buy haynes manual.

your rpm is a crank sensor either out of adjustment or you need one,located at crankshaft pulley,your aircon what do you mean not working