I just routed and installed my GEX P10XMT XM unit to my D3. After spending an hour routing the cable very nicely hidden, to my horror I realized I routed it so the blue end was towards the XM unit, and the black end was towards the head unit.
When connected this way the head unit seems to detect the XM unit, but I get no sound. I get sound from everything else just fine.
Anyone know if the IP bus cable matters if it is installed backwards like this?