If by pre face-lift you mean a 2015 yes. I finally got it to work, but It was a process. If it helps anyone else here is what I did...
After installing the new trunk I realized the harnesses in the trunk were different. using a wiring diagram easily found on the fourms I de-pinned the Harness from the both trunks, and repinned the New trunk, with the old harness. This took care of the Trunk latch opener and the license plate lights, However this left me with the 4 wires that power the backup cam system.
I identified these wires and labeled them, and left hanging.
Now to pull the signals from my existing head unit I
grabbed this adapter off amazon.
Thanks to user Nick I finally found the wiring diagram for the 16 pin that goes into the Head unit . -
Quote:
Originally Posted by NickB34
How are the wires hooked up on that 16 pin connector? If I'm remembering correctly, they connect the parking brake to ground and do a bypass on the signal.

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Using the above info I was able to determine that these 4 wires on the left would be the ones I was dealing with to run camera. ( I left nearly all the wires inrtact though just in case)
I labeled 4 long wires at each end, to match up with my labels in the trunk, then cut and stripped the 4 from the harness. I spliced them into the correct position and soldered them all up, then heatshrink.
I also Snipped off and capped the Yellow Male video connector, as that signal was already provided in the harness from the head unit.
(There is also a supply 6v+ single red wire coming from the harness. I had to clip it, and cap the end with shrinkwrap as it would inadvertently contact some bare metal behind the HU and that would kill the camera feed)
Next I unplugged the 16pin from my head unit (the one that has a single grey wire) and plugged that into the amazon harness that I just soldered. Then Plugged that harness directly into the head unit.
Now I ran the 4 long wires (remember they were labeled at both ends) all the way back to the trunk. I followed the many videos online about running wires in the 86. A $2.99 trim puller set from harbor fright was my best friend here..
Finally, one at a time I snipped the excess wire, then matched up my labels, and soldered in the trunk each wire. This was the toughest part, just because soldering in the trunk is hard enough, not to mention the wires themselves were short and closely bunched to begin with. This is a poor pic, and ultimately I cleaned up and zip tied the install nicely.
After that It was as simple as putting trim back on, and It is good to go. I Should mention I have only just taught myself to Solder (adding the valenti 3rd brakelight to this car) so I am by no means any expert, and I was able to handle it, just go slow.
The one problem is: 2015 head units broadcast parking lines (cannot be turned off in options)
2017 Head units do not, but 2017 OEM cams DO show parking lines. As a work around I just used the head unit options to get the lines as close together as I could. It is still a bit offset, but I can live with it. Some cams have a small wire you can snip to get rid of the in-cam park lines, but I did not see on this one. I could also swap out the cam itself with a non-line cam if it really starts to bother me.
So Viola! A stupid complicated answer to a problem that shouldn't be so hard... lol