Unfortunately my X3 is pre-LCI. However, I'll see what's up with the cable on the E70 X5 this weekend, since that vehicle has heated rear seats but no rear climate control, so it'd be a similar setup.

For the X3, I do know that the panel in the back of the centre console is slightly different to accommodate both the AUX and 2 seat heater switches.


Mittelkonsole High - BMW Teilekatalog