I read the post I still couldn't figure out the puzzle of where the oem wires fit into the aftermarket light & thought it might be different from 2013 to 14.
Green is Ground
Yellow Is Brake Pressed in Light
Black is normal brake light with out pressing the lever
Red is Right Flasher
Blue is Left Flasher.
I have a 2014 300.
This is as simple as I can make it, when you cut your stock taillight wire you will see 3 wires, 1 red, 1 blue and 1 black. When you cut your stock signal wires, you will see the signal wire and the ground (Cant remember off top of head what colors they are) Here is what you do:
Black wire from stock taillight goes to green wire on china light
Blue wire from stock taillight goes to yellow wire on china light
Red wire from stock taillight goes to black wire on china light
(Please understand that I am not telling you to connect the two lights together, I am simply referencing the stock wiring harness. I lack basic communication skills. Though if you do connect the two lights to each other, post pics and we will help you figure out where the problem lies

)
Right turn signal, signal wire, goes to red wire on china light
Left turn signal, signal wire, goes to blue wire on china light
You will be left with the stock turn signal ground wires. I left these disconnected completely without issue. I wouldn't go to that "Mechanic" friend for any more mechanical advice, if he couldn't figure this out. All he had to do was apply 12v to each input of the china taillight to discover what they do.
I already had an aftermarket relay in place, so I do not know if it was necessary. I would be surprised if the signals worked with the stock relay