Fuzy

I replaced the (working) factory radio in my 1988 r20 Chevy suburban 454 with a pioneer mixtrax head unit I got the wiring adaptor kit and spliced it all together properly but the head unit doesn't come on at all. I replaced the fuse in both the truck and the head unit itself but still no luck.
when I checked it with my multimeter it showed proper ground but no voltage at all whether the car was on or not.

Any ideas? I have a bunch of commercial electrical experience but this one is stumping me. I'm new to car electrical, is there a way to hook it directly to the battery if I rig a fuse of some sort?