The wiring harness I have has two leads for illumination (one is orange/white and the other is orange/black). They are labeled as Dimmer Positive or Dimmer Negative (or something like that).

Does anyone know which one to use for the AVICs?

Thanks!

Orange / White lead from the Metra adapter goes to the dimmer lead on the Pioneer.

The purple wire on the wheel remote plug (the one that goes from the car into the stock stereo -- there are 4 plugs total) is used for VSS.