I just purchased a 2004 S500 4matic--when turning on the radio it powers up but the onscreen options are grayed out and after a minute or so the error message "system unavailable" pops up and the system powers down. This happens while the engine is running. Any ideas?

 

i'm a bit surprised it powers down since you can power a MB Comand unit on the bench to test it and it stays on. Does it stay ON when the ignition is off? At any time are you able to select FM vs CD input, or does it never really powers up (stays greyed out) no matter if the ignition is on or off?

 

I mentioned that this happens when the engine is running as I noticed in other posts that this condition appeared to be related to running the stereo while the engine was off, hence draining the battery. I wanted to clarify that this was not the case. Basically when I start the car and turn on the radio, about 10% of the time the Command unit starts up fine and Navigation, Map, CD Changer and Radio funcitons work fine with full functionality and volume. I do not have a phone attached, nor have I used the cassette tape function or TeleAid. The other 90% of the time, the Command unit seems to start up fine, but the screen is grayed out and there are varying degrees of functionality ranging from zero response to being able to only use the a select few buttons such as the "eject" button and in some cases the "back" button. Regardless of the degree of functionality when it starts up in this condition, within about 90 seconds an error message saying "system unavailable" pops up and then the entire system powers down by iteslf.

 

I've not ever seen this condition but my thoughts are that the comand unit is internally faulty.
If I were you I would remove it, find the 12 volts power pin and ground and keep powering it up on the bench until you figure out if it has the same symptoms. OR
read this thread that suggests its the AGW module.
http://www.benzworld.org/forums/audi...boot-w211.html

 

Thanks--looking forward to an interestng weekend project. Also, a new condition on the commute home last night. Command unit seemed to have full functionality for all components, but no volume. After following one of the links in the post you suggested, it seems to be symptomatic to a failed or failing component on the fiber optic link. I am also going to try to isolate each component with a fiber optic coupler and see if I can locate the culprit.

 

Yes, typically no audio (you said no volume but I think thats the same thing??) is because there is a break in the fiber optic. More than likely its a failed in-series module and not the actual orange fiber cable unless its been kinked by recent work.
Be mindful that you could in fact have two modules that have failed and that can trick your testing. When you isolate modules from the ring, try and remove as many as possible. You only need the COMAND and the AMP to get audio when using the radio as a source.
Then add back one module at a time. You make have to turn off and back on the COMAND and ignition to test the changes before you hear any sound.

 

I have a 2004 cl55, low mileage 25k totally unmessed car, if I leave in my garage overnight unlocked, when I start the the car the command comes up with sound unavailable and then shuts down,same thing happens no matter how many times you switch it back on, star shows no faults, and will not switch back on. I read on a forum to try locking car, leaving 10 secs unlock and then try command, I was amazed to find that the command then works perfectly, I now lock the car every time I leave it and the problem does not happen, maybe nothing like your problem, but thought worth throwing in.

 

I have my car parked outside temporarily due some mattress stored in my garage while we re-do children's bedrooms, so my car is locked overnight. I ususally turn the key and hit the radio power button, so I will make an effort to do a 10 count and see if that helps. Interestingly enough, the problem occurs in the morning when the car is cold. The weather in Washington state just jumped from the 50's to the 80's and when I leave work, the command system fires right up. The car is warm from sitting in the sun, not driving. I thought it may be a moisture or condenstion issue.