All the connection you would need are at the head unit, but the rear speakers are usually simpler to get at.
I thought there was a wiring diagram for the radio in the technical files area but don't see it. I know jzeiler has a copy somewhere maybe he can repost it.
Just found this thread go to post 3 to see diagram. http://www.bmwlt.com/forums/k1200lt/...g-diagram.html
SORRY FOR DUPLICATE (new to forum usage)
First of all, sorry for some bad English writing from France ...
Secondly, sorry to post again (duplicate) but found this much more recent post about nearly same problem (ie in my case, finding switched power supply from inside CD radio housing).
Are you sure that Pin 5 of radio plug is an output from the radio and not from the K12 ?
I'm facing a big prob today about this, and some 2012 post here.
I did use attached wiring diagram : wiring a standard 1A USB power converter (12v to 5v) to pins 15 for ground and 5 for switched power supply.
Actually this diagram shows Pin 5 is an input ("Eingang" german speaking) for the radio.
And, I'm not really sure now (after reading your post), but when I measured each pin voltage (before connecting anything !) I remember that this one was 12v (when key switched on) even without radio connected ...
My problem is that I had correct power for a few hours, but when I wanted to have a last test before reassembling everything, I had no more switched power on this pin 5.
So I do not know at this time if my prob comes from radio or from bike ...
But you can imagine in what state my K12 is at this time as I tried all day long to find where this switched power supply signal could come from (of course 7,5A fuse already verified) ...
A few post before (2012 year), Cochinosucio said that this pin could be fused (15A), but I have not any idea where this 15A fuse could be if it exists (inside radio, need to dismount) ?
I have to precise that my K12LT FL is a may 2004 one, and that the single CD radio is the only sound equipment I have at this time (it is a Becker Pro 2000 Ece 65.12-7 ...). But the attached wiring diagram seemed to match my bike one's as measured voltages.
I even did try to attache AUX inputs on Intercom plug, and it worked fine (except amplified sound) until switched power failed !
Any help would be greatly appreciated before I have to forget any idea of listening music sounds on my K12