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Discussion Starter #1
This may sound like a simple problem, but I could use a hand..

I installed a Sony RF mp3 changer in my 01 CLK55 yesterday, with all the connections terminating at the unit mounted in the trunk. Everything went smoothly, looks sharp etc., but I can't find an easily accessible switched ignition source back there. 12v constant is no issue as the battery is about 1 foot from the changer, but no lead in the nearby fuse block is switched. The factory changer connection (which I intended to use for power) has 3 leads; ground, 12v constant, and another (!) +12v constant. Seems odd to me, but that's what it measures.
So my question is simple- has anyone located a switched power source in a CLK trunk? There are several wrapped wire looms, but I have no desire to pierce the skin of each wire and turn the key on and off repeatedly as that approach seems a bit crude..

Ideas?
 

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One more thing to add; one of the +12v MB changer connections is 1 volt lower than the oth...

One more thing to add; one of the +12v MB changer connections is 1 volt lower than the other. Perhaps it is actually switched, but what the heck is keeping it at 11 volts with the car off..?
 

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Re: One more thing to add; one of the +12v MB changer connections is 1 volt lower than the oth

One more thing to add; one of the +12v MB changer connections is 1 volt lower than the other. Perhaps it is actually switched, but what the heck is keeping it at 11 volts with the car off..?
One is +12v from the headunit, one is ground, one is D2B wakeup (if you have COMAND, it's from the C2 connector pin 10; without COMAND, I forget what pin it is on the C connector). I don't think you want to be using D2B wakeup for anything.

Just curious, why do you need switched 12 volts for the CD changer? All the OEM CD changers (and other compatibles from Alpine/Becker) are always "on". They draw very little current except when in use. When not in use, the constant 12v allows one to remove the CD magazine.

-s-
 

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Re: Re: One more thing to add; one of the +12v MB changer connections is 1 volt lower than the

Thanks for the reply.
You're absolutely right.. but I would guess that the changer mfgr wants switched power as well so the unit knows when you've shut the car off. So a tune I'm halfway through will start up again later, and the changer won't continue to play when I shut the car off.


Just curious, why do you need switched 12 volts for the CD changer? All the OEM CD changers (and other compatibles from Alpine/Becker) are always "on". They draw very little current except when in use. When not in use, the constant 12v allows one to remove the CD magazine.
 

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Re: Re: Re: One more thing to add; one of the +12v MB changer connections is 1 volt lower than

Thanks for the reply.
You're absolutely right.. but I would guess that the changer mfgr wants switched power as well so the unit knows when you've shut the car off. So a tune I'm halfway through will start up again later, and the changer won't continue to play when I shut the car off.
Ah, the wonders of non-OEM equipment... ;)

This functionality is achieved with the D2B wakeup line.

To correctly duplicate it (because you want the CD to stop playing if you shut off the radio, not just the car, also you can turn on the radio with the car off), you need to use the remote power lead from the head unit. You'll have to run a wire back from there.

I think you're looking for connector A, pin 5. It's really not that hard to correctly run a wire from the head unit into the trunk, so don't take short cuts on it!

-s-
 

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Re: Re: Re: Re: One more thing to add; one of the +12v MB changer connections is 1 volt lower

Ah, the wonders of non-OEM equipment... ;)

This functionality is achieved with the D2B wakeup line.

To correctly duplicate it (because you want the CD to stop playing if you shut off the radio, not just the car, also you can turn on the radio with the car off), you need to use the remote power lead from the head unit. You'll have to run a wire back from there.

I think you're looking for connector A, pin 5. It's really not that hard to correctly run a wire from the head unit into the trunk, so don't take short cuts on it!

-s-
Thanks again.. your initial post gave me an idea. I disconnected and used the 11 v lead as a spare conductor to the trunk (already ran the changer control head cable to the front so the car was put back together) and tied it in under the dash to a switched source. Easy to reverse if need be and works great. Sound quality is good, though certainly not like a traditional CD changer. But the MP3s are compressed anyway :)
 
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