Help with DIY speaker project

Hi all, first post so hopefully this is in the right place.

I'm making a semi portable Bluetooth speaker. I may add batteries at a later time but for now I'm using a old PC PSU to run an stereo out of a VW van / combi bus as these are the parts I have seen lying around.

The problem I have is I don't have the wiring harness and can't get the stereo to power on. I've found this pin-out info:

I think I need 12vDC to pins 11 and 15 with ground to pin 12 all on the A connector but not getting any joy.

Am I missing something? Bit unsure about the code / safe pin which is 16.

I'll try and add photos

Any help greatly received.