Hello there, I have a 2014 E350 that has the dreaded audio issue, I have replaced the Sirius receiver in the trunk and just replaced the amp and still do not have power going to the amp. Checked all fuses, went in engineering menu and made sure everything was correct there. I dont believe it is a fiber optic issue because I have light going in the amp and in Sirius receiver. Does anyone have any recommendations on what else to check? I have been without sound for 4 months and its driving me crazy. Thanks for any help you can provide.

 

See attachment for overall network inclusive of MOST.

 

Thank you for your response and the attachment. I am not sure what I am supposed to do with though..Can you elaborate on that a little please?

Thank you

 

those diagrams are showing just how complex this car's computer systems are, with multiple units interconnected with digital data busses (10 different CAN busses!) as well as fiber (Media Oriented System Transport, MOST). About the only way to diagnose this is to have the full XEntry Diagnostic System and dive into those data buses to see what is going on. The head unit A2 is connected to two different CAN busses for command and control, and 4 modules via the fiber MOST for actual audio. ALL this has to be working perfectly for this system to operate.

 

How can I check to see if the amp is getting power? The fan is not moving on either of the amps I have...

 

have a mechanic hook the car up to the XEntry Diagnostic system and read any and all codes associated with the media system. Said mechanic should have access to the wiring diagrams in WIS (I sure don't have that), without wiring diagrams its impossible to diagnose stuff like this.

 

As its been alluded, it's not as simple as power and ground... though I guess if could be if one of those was the issue. With any module your diagnoses usually does the following:

• Scanning for codes and review live data
  • Running built-in tests (if available)
• Check for power and ground (could be multiple) at module
• Verifying CAN
  • Ideally with scope, otherwise is some form of continuity, resistance and "average" signal voltage

Attached is a wiring diagram for the amplifier, should verify with your VIN, but should be good up to March 2015 (basing that on MOST bus being <3/15 in the "diagram tree"). I see power being fed from Fuse 67 off rear SAM to Pin 1 (of main connect, not 2 pin MOST) and a ground on Pin 2 of amplifier. That's about it, besides connections to speakers, maybe a couple CAN signals and MOST.