I bought a turn signal a long long time ago because my front driver's side one was rusted and didn't work. The one I ordered is in good shape but the "plug-in" part is plugged into the part from a different car; person I ordered it from just cut the wires instead of disconnecting it from the car.
I'm trying to decide if I should just cut the wires before the plug-in on the turn signal I bought or cut the wires on my driver's side turn signal.
Not really for sure how it works, so I don't want to cut mine up and then just be F'd all together.
Not for sure if I described my situation good enough, I'll try to take pictures.
It is a s5 n/a btw. If that makes a difference in how the turn signals operate.
Also by driver's side, side marker works so I know it isn't a grounding problem or w/e.

 

A bit confusing, but it seems like the new harness you got doesn't have the other end that goes on the chassis harness on the car? Either way it seems you still have to cut some wires to get the harness in there. No harm in that if you do it properly.

Use shrinkwrap and solder your connectors and you ill be fine. Try to keep the the chassis harness as it is and only cut into the actual turn signal bulb harness.