When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
My car exhibits the same exact symptoms (no audio, devices unavailable, can't see any radio stations, etc.) however it usually starts working again after a few days.
absolutely NO point doing any investigating, swap out the amp with these symptoms its 100% at fault, they die over 6 months some days all good other nothing. The first time it happens just get an amp and get over it once and for all
My car exhibits the same exact symptoms (no audio, devices unavailable, can't see any radio stations, etc.) however it usually starts working again after a few days. It definitely seems to be moisture related, however I've taken the amp apart and there is no sign of moisture damage anywhere. I've inspected the interior compartment that the amp sits in and couldn't find any sign of moisture anywhere. I believe it's moisture related because it fails after there's been rain or snow sitting on the car.
Does anyone have a list or diagram of the MOST ring on a W221 (2011 S550) that would help me troubleshoot other modules on the loop? I have a MOST bypass adapter that I would like to try.
You should use the loop with the SiriusXM module, just in case you will be able to use cd and USB for audio, something 2011 not just the amp goes bad, the module is one of the main problems in those models.
You should use the loop with the SiriusXM module, just in case you will be able to use cd and USB for audio, something 2011 not just the amp goes bad, the module is one of the main problems in those models.
Alexander,
thanks for the input, the next time it goes out, i will try and bypass the XM module.
I have a W221 S550 2008. Before posting, I have read through many many posts looking for a solution to a dead MOST ring. I get an error message of D104 with accompanying comment of "open ring on position 4". I also got a message on my screen that says MOST system will shut down in 3 seconds due to low power. I have checked every fuse in the car. Nothing seems blown. I have not checked the pre-fuse modules (cant find the exact location of Pre-fuse modules). Checked both batteries and I am getting enough power from each when I tested them at the terminals.
The screen is dark with absolutely no functions available except the climate control. The CD player is absolutely dead..
Suggestions anybody? I would certainly be really appreciative for any pointers. Thanks all!
Did you check the auxiliary battery. Sometimes if the auxiliary battery is going bad the car will shut down other functions it doesn’t need to keep the car driving
Are there lights on the cd changer? Usually if the MOST ring goes down, the CD changer still has lights and you can load or eject disks. If it’s completely dead, that may be the source of the problem.
ive never gotten the low power warning, that sounds like a good sign... like a fuse has blown or a bad ground somewhere. Not a completely dead module.
buy a MOST bypass loop off amazon and bypass all modules you can reach.
Hi Benzton. I checked the Aux battery at the terminals. They seem to put out 12.4 volts and charges up perfectly.
Hi CStevenson, There were lights on the changer. However those disappeared once I started pulling fuses. There were no blown fuses. Now everything connected via MOST is dead, including the back up camera.
My feeling is that is one of the pre-fuse modules. However I dont know where they are located. I think I should check that before I take it into the garage. I ran a diagnostic on my Autel scanner and I get the message of "D104 : Open Most ring on position 4". On a couple of occasions I have got the message of MOST has shut down due to low/high power. This compliments the message of low power that I got on my car screen.
Hmm, I believe each individual module will monitor its supply voltage and post a fault if too high or low. It’s odd that MOST itself isn’t posting a fault.
it shouldn’t be too hard to track down the component at position 4.
Any ideas on which module would pertain to position 4? MOST is posting a low/high voltage error on my scanner. The car itself itself give me the error of low voltage. Unfortunately it does not give me information on which MOST module is posting a open ring, neither does the scanner.
Any ideas on which module would pertain to position 4? MOST is posting a low/high voltage error on my scanner. The car itself itself give me the error of low voltage. Unfortunately it does not give me information on which MOST module is posting a open ring, neither does the scanner.
did you end up figuring out the issue I have the same problem !
Unfortunately I have not. However my Audio seems to have come back on line other than the occasional drop in power which turns of the system for a few mins and then comes back on. Like something is resetting or not getting power for a few brief second. I have not had the chance to explore this further. I have given up and the car heads into my mechanic on Friday. Il will post updates when I have it.
Unfortunately I have not. However my Audio seems to have come back on line other than the occasional drop in power which turns of the system for a few mins and then comes back on. Like something is resetting or not getting power for a few brief second. I have not had the chance to explore this further. I have given up and the car heads into my mechanic on Friday. Il will post updates when I have it.
I have had the loss in power for a few days and then back to normal. I took it to the Benz dealer and was told I need anew amp for $2400. Then I did research and found Alex Nunez of JP Auto. I too thought it was from moisture, found no moisture, then I thought maybe because of street potholes. When I spoke to Alex we spoke electronic tech to electronic tech(each other) language. So bottom line your amp receives the power and distributes the power to other audio devices. The PCB board in the amp is the issue when it comes down to it. I sent mine to Alex Nunez at JP Auto in upstate NY. He rebuilt it for me and sent it back within the same week. Good quality work, excellent communication, HIGHLY RECOMMEND JP AUTO BY ALEX NUNEZ SHOP#315-543-4555.
If you want this fixed ASAP call this guy
I have had the loss in power for a few days and then back to normal. I took it to the Benz dealer and was told I need anew amp for $2400. Then I did research and found Alex Nunez of JP Auto. I too thought it was from moisture, found no moisture, then I thought maybe because of street potholes. When I spoke to Alex we spoke electronic tech to electronic tech(each other) language. So bottom line your amp receives the power and distributes the power to other audio devices. The PCB board in the amp is the issue when it comes down to it. I sent mine to Alex Nunez at JP Auto in upstate NY. He rebuilt it for me and sent it back within the same week. Good quality work, excellent communication, HIGHLY RECOMMEND JP AUTO BY ALEX NUNEZ SHOP#315-543-4555.
If you want this fixed ASAP call this guy
Might be off topic as to which module is position 4 but i bought online fiber optic bypass (less than $10). Removed side panels in trunk and started with modules. I found that moisture has indeed gotten in.There are funky trim tabs (instead of normal push pin type it is almost rubber like that is an elongated closed tube that the push pin goes in to seal) that secure the rails that run along the side of trunk between the fender and opening of trunk (that are covered by closed trunk deck/lid). The connectors on the satellite and bluetooth had corrosion but the satellite (many models use that same module and cheap on ebay) was bad. You put the fiber optic bypass at each module one at a time. Then turn the car on, if the loop is complete the radio will work just not the bypassed module. Atleast that is what I had to do. My nav worked, just when push radio/sat etc would say device unavailable, cd would load but not play. I thought it was the amp but wanted to test modules first.
Hello everyone...After reading this thread a little bit I feel compelled to chime in on behalf of Alex @ JP auto sound. The man is a pro, and gave me an obscenely awesome deal on an amp for my 2008 S600 Carlsson. Price so low my jaw dropped. I met up with him in the Bronx when he came down to visit some family for the weekend and handed him my blown amp, he handed me an expertly repaired exchange.
Last month I started hearing constant popping noises on all speakers. He offered to replace my amp, but first asked that I fiber loop the voice module as it may be bad. BANG, HE NAILED IT. Bought a voice module on Ebay for $50 and no more popping noise and can use voice commands now (no need to program voice module).
With him on this thread guys, there is absolutely no need to refer to M&B audio repair....Alex will not only beat their price, but he is also a man with integrity and takes pride in his work. I can vouch for him....Jeff
Hello everyone...After reading this thread a little bit I feel compelled to chime in on behalf of Alex @ JP auto sound. The man is a pro, and gave me an obscenely awesome deal on an amp for my 2008 S600 Carlsson. Price so low my jaw dropped. I met up with him in the Bronx when he came down to visit some family for the weekend and handed him my blown amp, he handed me an expertly repaired exchange.
Last month I started hearing constant popping noises on all speakers. He offered to replace my amp, but first asked that I fiber loop the voice module as it may be bad. BANG, HE NAILED IT. Bought a voice module on Ebay for $50 and no more popping noise and can use voice commands now (no need to program voice module).
With him on this thread guys, there is absolutely no need to refer to M&B audio repair....Alex will not only beat their price, but he is also a man with integrity and takes pride in his work. I can vouch for him....Jeff
Yes. Alex at JP Auto Sound is the man. To all that read this article or thread call this guy for all your MB audio issues. The best in the business I’ve seen thus far, reliable, trust worthy check him here is his info
JP AUTO SOUND
8417 OSWEGO RD SUITE 168
BALDWINSVILLE, NY 13027
Phone: (315)543-4555
website: www.jpautosound.com
Last edited by henrydarryl52; Jun 5, 2020 at 09:27 AM.
I assembled some information on the MOST system from WIS and am providing it here, I hope it helps some people.
If your MOST ring goes down, I'd recommend buying a MOST bypass adapter off Amazon and bypassing components one by one until the ring goes back online. This should save you a trip to the dealer, and their diagnosis fee. Hopefully, this method is also more definitive than a "MOST ring open at position #" code. Below is a wiring diagram for USA market vehicles (MY 2011, but it should be the same for other years as well). Amplifier is the MOST controller, and dies frequently as everyone on this thread has pointed out, so I'm not sure what will happen if you bypass it when it's dead. I think the modules communicate independently, so you may still be able to view iPod songs in COMAND (for example) if the amplifier is dead. Bypassing other dead modules should allow the MOST ring to function, it will just list the bypassed module as unavailable.
Amplifier - MOST controller, located in left side of trunk, dies frequently
Satellite Radio - In trunk, optional equipment
Media Interface - Beneath passenger footrest, optional?
CTEL - mobile phone, optional equipment
Voice Control System (VCS) - In trunk
Digital Sound Processor - Optional, for cars with the upgraded stereo
COMAND - The CD changer in the dashboard
Last edited by cstevenson; Jun 5, 2020 at 06:14 PM.
Reason: Added VCS removal instructions
2012 S550 . Recently my command center has gone out and my display screen does not power on, not even a logo. i have checked all fuses leading to command and are good, even reset positive battery still did not help. Can anyone lead me in the right direction please? Thanks!!!
2012 S550 . Recently my command center has gone out and my display screen does not power on, not even a logo. i have checked all fuses leading to command and are good, even reset positive battery still did not help. Can anyone lead me in the right direction please? Thanks!!!
Those units most of the time lost the firmware, probably you may need to reprogram the unit.
[QUOTE=henrydarryl52;8074111]Yes. Alex at JP Auto Sound is the man. To all that read this article or thread call this guy for all your MB audio issues. The best in the business I’ve seen thus far, reliable, trust worthy check him here is his info
Last edited by alexander nunez; Oct 19, 2021 at 10:14 PM.
new address:
JP AUTO SOUND
8430 OSWEGO RD SUITE 168
Liverpool, NY 13090
Phone: (315)967-4352
website: www.jpautosound.com
anyone know if Alex is a member on here, as I have been trying to call but having no luck reaching anyone. As well does anybody know his prices for a new amp without exchanging the old one?
edit: Alex just called back! Exactly as everyone says, his prices are unbeatable... $500 for a refurbished and repairs at $350, and I believe he stated exchange was $400 or $450! My old amp is stuck out of state at the moment so may have to role with a refurbished amp!
Last edited by charmessence; Feb 3, 2021 at 01:09 PM.
Hi everyone,
Can someone please Help? I have a message on my radio that says device unavailable and the radio doesn't work. It was working fine and all of a sudden it stop. What could be the problem? Is this something that I can unplug and it start working again?
Hi everyone,
Can someone please Help? I have a message on my radio that says device unavailable and the radio doesn't work. It was working fine and all of a sudden it stop. What could be the problem? Is this something that I can unplug and it start working again?
Update JP Auto Sound231 Sherwood CirRock Hill, SC 29730Tel. 803.504.4397
I believe he moved to SC.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
MOST Information
