Does anyone know what the differerence between Illumination (+) [pin 1] and illumination (-) [pin 7] is? I connected the "illumination power suppy" orange/white wire from the head unit to the orange wire in the Metra wiring harness, which connects to pin 1 of the factory harness. I am installing a new Eclipse head unit and the display on the new radio doesn't dim when I turn on the headlights. Thanks.