I've tried searching on the internet and can't find a wiring diagram.

I have a constant but no other power Ie: ignition

Its an 8 pin connector, 4 x 2

top 4 are

Pink (speed) blue w/yellow stripe (unknown) yellow (unknown) black (ground)

bottom 4 are

purple (reverse input) blue w/red stripe (monitor control out) red (unknown) orange (constant)

any ideas?

G90 ? Don't you mean the F90? If so here's the wiring diagram for it. http://www.pioneerelectronics.com/Stati ... al0520.pdf