Perhaps it'll help if I post what I'm looking at and my best guesses thus far for what's what. Using the pin numbering labled on the plug and head unit:
1 - pink/black ... illumination
2 - black ... ground?
3 - pink/black
4 - blank
5 - orange/red ... rear right +
6 - gray/pink ... rear right -
7 - white/green ... front right +
8 - green/orange ... front right -
9 - green/purple (thick) ... constant 12v?
10 - yellow/black
11 - black/green (thin) ... ground?
12 - gray/blue ... rear left (l/r?)
13 - brown/yellow ... rear left (l/r?)
14 - orange/green ... front left (+?)
15 - blue/white ... front left (-?)
16 - black/green (thick) ... 12v accessory?
where the orientation is represented here with orange being pin #1:
Between that picture and the similar one (different manufacturer, though) here:
and these charts:
I filled in as much as I could above. That gets me pretty close, but I'm a bit nervous experimenting blindly, not knowing which is power and ground...