No apologies necessary! I also have the same diagram from years ago. This is why I posted. The Volvospeed mostly talks about the HU units that I know are different than ours. I also found a pretty interesting solution from Monster Cable. They sell a little box that talks M-bus as do our head units and CD changers as far as command interface. They charge $150 for the box and then about $30 for the cable that goes from the box to the head unit. Then another cable from the box plugs into the iPod and then you control the iPod from the head unit as if it were a CD changer. Instead of disks you change playlists and you can use CD changer controls on the head unit to skip through songs in the playlist as if they were songs on a CD. It's cute, but a) pricey and b) you must loose the CD changer. If what I am thinking about works, the CD changer will stay put and you will be able to switch the aux piece of equipment (not just iPod) in and CD changer will automatically be taken out of the audio path. The controls will need to be worked on the aux piece of equipment, not via head unit. I will be blowing dust off my oscilloscope shortly to find out if my plan will work. If it does and I have a prototype, I'll report.

Thanks!
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Vladimir. '98 S70 base, 5-speed manual - his, '93 945 (approaching 200K miles and rolling on...) - hers