Chevy & GMC Vans

so theres more then just the standard listed wires in the harness i'll list what i know and we can add more as we go...sound like a plan... lets id all the wires in that pesky radio harness

Constant 12V+ -Orange
Switched 12V+ -Yellow
Ground -Black
Illumination -Gray (next to purple/white)
Dimmer -Brown

Front Speakers 6 1/2" Doors
Left Front (+) -Tan
Left Front (-) -Gray
Right Front (+) -Light Green
Right Front (-) -Dark Green

Rear Speakers 6 1/2" Rear Door
Left Rear (+) - Brown
Left Rear (-) -Yellow
Right Rear (+) -Dark Blue
Right Rear (-) -Light Blue


(just to help)Typical Head Unit Wire Harness

Function Typical Wire Colors
Memory / Constant 12V(+) - Yellow
Switch / Accessory -Red
Ground -Black
Illumination -Orange/White
Antenna Remote -Blue
Amp Remote -Blue/White
Left Front (+) -White
Left Front (-) -White/Black
Right Front (+) -Grey
Right Front (-) -Grey/Black
Left Rear (+) -Green
Left Rear (-) -Green/Black
Right Rear (+) -Violet
Right Rear (-) -Violet/Black


so i know on the power side of the radio plug there is a purple/white wire that isnt spoken for..
and im not even sure about the speaker side of the plug...i'll find that out tomorrow

Well my thought are dimmer for interior lights - I have a wiring diagram I'll post - had it up but the link is broken

interior light dimmer on the radio plug? if u mean the one to dim the radio lights that is brown. my thought is one of the five remaining wires is a turn on for the factory amp (could be wrong)