DIY - Aftermarket Head Unit install on 2017 BRZ

[itsAlex]

Originally Posted by Pizzachicken

I was stumped earlier as I had bought the 28-pin adapter (Metra AXSUB28SWC6V) and I too have an FRS, was following this writeup for the BRZ. Seeming that I theres no use for retaining anything from the 28 pin, I'm planning to repurpose it to plug into the 24-pin. Just making sure with you, there's no cables to connect from the 28 to 24, right? The reverse input would be the red cable on the 24-pin (#2)?

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Edit: For future reference if anyone finds themselves in my situation, follow Alex's diagrams, where the only extra step is to tap into the reverse signal from the 28-pin connector, wired to your head unit's reverse wire.

Sorry for the late reply, but yes I believe the only thing useful from the 28-pin connector is the reverse signal. It's been a while since I did this install so my memory is a little rough here.

In your post you mentioned the red cable on the 24-pin connector for reverse signal, did you mean 28-pin connector? I don't think my reverse signal came from the 24-pin connector, I believe I used the signal from the 28-pin connector.

[ymshulman]

I just received a Joying unit (11.6") with their Toyota Hilux harness - which doesn't actually have the wires labeled well - , and there are a few things that I could use some help with to install this into my 2017 BRZ. (Once I get this in, I'll be able to share photos of how it looks installed in the car - it's a pretty big unit, but not quite as overkill as the 13" units.)

Attached is a photo of the harness.

1) It seems like they left the amp unpinned, leaving it to me to pin it where it belongs for my car (pin 9 on the 28-pin, I believe). (I don't see anything on the 28-pin connector that looks like the amp wire, and I think what's labeled 'amp-connect' is this.) But the wire is just a bare wire - it doesn't have those pin ends the the other wires in the harness have. Am I missing something? How would I pin it in? (Update - this is indeed silly of them. They should put a pin on the end of it, so we can just stick it in the appropriate harness for our car. I took one from the extra 20-pin harness.)
2) I apparently need to find another RCA cable to connect something to the backup camera input wire on the Joying headunit - since I'm using the OEM camera, which doesn't have an RCA cable. Can I just strip any RCA cable, and connect the wires inside it to the appropriate - and + wires? (I did purchase the DROK 6v-12v converter, so I'm ready to go there.)
3) The radio harness has me confused. It has the large round cable and a blue cable - which I've read is supposed to connect to [pin on the 12 pin connector] - but that connector is currently full. There does seem to be an odd set of connectors on the end of that blue cable, and on a wire sticking out of the 12-pin connector. Do I just... stick those together?
4) Why on earth are there 2 sets of aux-in cables... one on the 28-pin connector, and one on the 20-pin connector? (Edit - because the 20-pin is not used for this car.)

[ymshulman]

I worked out some of my questions above. But I still have some questions:

For the backup camera, the guides have 2 wires for signal. Are those signal and ground, or + and - from the signal?

- I want to repurpose an RCA audio cable for this (since that's what I stripped out of the extra 20-pin harness, and its wires are already pinned for a harness). That has ground, + and -. Can that be repurposed for the video signal - and if so, do I just ignore the ground, and route the + to pin 12 and - to pin 13?

- Can the black ground wires on the DROK converter be wired to any ground? Or do they specifically need to be routed to the ground wires specified here? (Asking because I don't have enough pinned wires - I'm trying to make do with what I have. If anyone has an extra pinned wire they are willing to stick in an envelope and mail, I'd definitely appreciate that!)