So Im putting back my led headlights back on my z and realized that I lost the wiring for the leds for one side. I found the led bulbs, socket but theres this small black box that I cant figure out what it is or where to get it. Can anyone help me out

 

I'm not sure what that is exactly, but my guess would be a box with resistors inside. Usually when you add LEDs to a system that uses regular bulbs it throws an error because LEDs require significantly less power and that is seen by your electrical system.

Someone correct me if I'm wrong!