having just wired an active sub into my wonderful new green '03, and fitted 6x9's in the rear bins. Here is an overview of the wiring out of the stock head unit.
blue/yellow: +12 volts constant
grey: +12 volts switched
brown: chassis ground
green: +12 volt illumination
white/green: +12 volt dimmer
pink: LF+
purple: LF-
light Green: RF+
dark Blue: RF-
Black: LR+
yellow: LR-
red: RR+
white: RR-
Hope it helps.