marko69

Anyone know what the "wake up" signal for the sound amp is? i.e. 12vdc, ground, data. The signal comes from the stock radio (2004 D2B) and I'll be replacing it with an Android unit and a stock 2005+ most amp. I'm assuming the wake up signal will be needed to turn on the amp so I need to copy it, bypass it or trick it.

Rudeney

It's a digital signal sent over the CAN bus. If your radio does not communicate via CAN and MOST fiber, you will not be able to use the factory amp.

bobterry99

It can be either a digital electrical signal transmitted over a dedicated wake-up line to each component in the optical ring or an optical signal over MOST. I believe in your system the component which interfaces your Android head unit to MOST will need to source the wake-up signal.

Here is a MOST inteface which may or may not incorporate wake-up: http://www.installer.com/item/displa...?it=most-hurmb.

Rudeney

Bob is correct - I said "CAN bus", but it's done via the fiber.

marko69

Bob I believe you are essentially correct.
I found a few docs in the WIS about the wake up function.
This is how I believe it works.
When the key is turned on or the power button on the radio is turned on, the audio gateway sends out a short duration electrical pulse on a separate wake up line to each component that is part of the MOST ring. Each component then replies optically to the audio gateway over the MOST ring. If the audio gateway does not receive a reply from a specific component, it then makes several attempts to wake up the component optically.

There is one important contradictory sentence in the first paragraph in the Most wake up description: In order to do this, the audio gateway control unit (N93/1) transmits a light signal via the MOST ring. Read the "wake up most" pdf I've attached and I think you may agree with me.
If this were the case, then the rest of the document doesn't make sense. The D2B wake up document is very similar but it clearly states that the master unit sends out an electrical pulse on a separate wake up line to all components to wake up the D2B ring. I believe the master unit is the Radio in this case.
None of this really helps as the WIS doesn't say exactly what the electrical wake up line signal is. I've also attached a document from one of the forums which says it is a 12v signal. Other threads I've read says it's a 5v logic signal.
I've attached the WIS documents and one document for a W211 that I think is relevant.

Bob, if the opt1 were to put out a wake up signal, that would certainly be the ticket. For $549.95 I would certainly think it should, but I haven't read anywhere that it does. Haven't read that for the xtrons unit either. I wonder if adding an Audio Gateway just for the wake up signal would do the trick.

bobterry99

The specifics of the MOST wake-up are slightly unclear.

The Electrical Troubleshooting Manul (ETM) states there is "no reliable test" for measuring the signal on the wake-up line. Perhaps with an oscilloscope you could observe and characterize it and reliably duplicate it.

I believe adding the Audio Gateway could provide the needed wake-up function. If so, you may need Star Diagnosis to code the gateway with the MOST ring architecture.

If I were going to replace the COMAND in my '03 with a modern aftermarket unit, then like you I would choose to keep the factory amp and speakers. Those components have been customized to work with each other in one specific vehicle. I don't think I could substitute aftermarket components for those originals and expect the sound to be as good. Caveat: an impressively loud bass that is distorted and exaggerated is not my idea of good sound.

marko69

Absolutely right. I very much want to keep the factory amp and speakers because of the reasons you mentioned. I have already bought an '05 amp and an android head unit but I'd like to wait on buying the rest until I can figure out this wake up business. I do have an oscilloscope and was thinking about checking one of the easier to get to components and checking the blue/black wire. I was hoping someone had an answer before I did too much work!!
With the audio gateway, I was just thinking about connecting switched power to it then connecting the blue/black wire to the amp and nothing else. My hope would be that when the AGW turns on, it will send the electrical wake up signal to the amp and turn it on.

S_W222

@marko69 @bobterry99 @Rudeney
Any updates on this? i have the same issue, i can't seem to process a "wake up" after I installed an aftermarket android unit..... :S it takes 5-7 min for sound to start coming ... am sure it's something related to the wake up signal

marko69

I gave up on it. I was not able to bypass the wake up signal function on the amplifier board and I was spending way too much time with this. I'll just be biting the bullet soon and get an aftermarket amp and possibly speakers.

S_W222

in my case, the sound comes after. 5 min, is it the same in your case?
also, aftermarket stereo worked for so many others just fine with a decoder, why it it only me and u?

S_W222

I tried before it connect the ACC of my decoder device, to the wake up signal, and it worked, BUT, this has kept the decoder the CAN BUS working overnight and caused battery drain. The wake up line from the car harness is hot all the time and any device you connect to it is going to stay awake overnight.... did you mean to connect the B+ of the decoder to the wake up line? or the ACC of the decoder to wake up line?

S_W222

I know that my idea seems crazy, but am thinking about brining the original COMAND unit, give it access only to battery, ACC and connect the Wake up signal to it, and leave it in the trunk so it sends the wake up signal; always... i will keep the speaker lines and fiber optic connected to the new android stereo as well as a secoundery battery and ACC signals it needs.... .thoughts?

marko69

That may not work. On the '05 amp, the wake up signal comes from the Audio Gateway, not the radio. I looked around for a used audio gateway but couldn't find a cheap one to experiment with.

S_W222

@marko69 I think you misunderstood me.... what I meant is that I am going to connect the original car stereo to the audio gateway, this way the original car stereo is going to respond to the wake up signal and tell the audio gateway that the comand unit and audio is needed..... on the other end in parallel, am going to have the Android stereo connected to the speakers and fiber optic decoder to send audio/music by the time the only function of the original car stereo is going to be responding to the wake up signal and confirm the need to activate the amplifier

marko69

Maybe I have assumed too much. To be clear, your original system is a MOST system, as you have an Audio Gateway? The DB2 system (my car) doesn't have one.

marko69

If you already have the MOST system, yes that sounds like it should work.

CXXXV

I'm hoping someone will see this. I have a 2008 GL450. I'm having the same issues as you guys reported above. I installed an aftermarket headunit. The fiber optic decoder is a MOST-PC/ML. The headunit has a connection labeled AMP-CON. What I read was that this should be connected to the ACC of the decoder.

As you guys have mentioned this is supposed to Wake-Up the AMP. But it does not. As marko69 reported it comes on after about 5 mins. So clearly whatever signal is required it's not happening.

Has anyone found and answer. I been doing web search for days.

g0rsq

MOST System Training document.