I now have the relay installed. It works perfectly. The Z1 now knows when I am in reverse. To make the install easy I purchased the relay with a socket from PartsExpress.
12VDC Bosch Relay 30A, part number 330-070, $2.64
12VDC 5-Pin Relay Socket, part number 330-075, $1.75
It cost about $8 to ship them
Here is a breakdown on the wire connections. The first number is the number on the socket.
85 Black - ground
86 White - power that energizes the relay - connect to car reverse wire
87 Yellow - hot when relay is energized - connect to pioneer purple wire
87a Red - hot when relay is not energized - not used (cover wire)
30 Blue - input power - connect to wire that is hot when car is running
At first I was going to try and install the relay in the spare tire compartment since I needed to tap the reverse wire there. I changed my mind and decided to put it in the amp compartment. First I tapped the reverse wire. There are two reverse wires, I tapped the yellow-white one.
I ran the wire tap into the amp compartment.
Inside this compartment was a few screws near the brake lights (or whatever they are). I used one for the ground. I couldn't find a source for the input power so I tapped into the wire that used to power the amp. This wire is always hot even with the car off. I prefer a wire that is only hot when the car is running but in this case it is not a problem because the relay will not pull any juice since the Red wire is not connected to anything. If you decide to tap the amp wire be sure and remove fuse 72 (located where the sub-woofer is [or would be] located).