OEM Reverse Camera and aftermarket head unit

[map26]

Hi All,

Just wondering if someone could help me out. I've tried most of the morning to work this out and it seems to have stumped me. I've checked as many forums /posts as I could to help solve it but nothing yet.

I just bought a 86 '15 (Australian model) and had the reverse camera came standard. I'm replacing the Toyota Head unit with a Pioneer 8650BT. Have the wiring harness and that's all sweet and sorted.

Issues are with the reverse camera. Below is a pic of the cable (CN4950).

Here's what I've tried:
1. Hooked up the black wire to the chassis negative grounding wire on the harness (using a 12v to 6v converter)
2. Hooked the yellow (VA -) and white (VA +) to a male RCA cable and direct feed in to the HU

I'm not sure where to connect the red wire (CA +)

Or have i got it totally wrong and the ground should stay with ground 12v and the red should be connected to the 6v converter?

Also, how do I set it up so it knows that I'm reversing and shows the reverse camera?

I was using the below for my wiring harness set up (Metra).

Thanks in advance.