License plate light, Help please?

Hey guys, I just put on my new 2 bros exhaust along with the supplied license plate holder, turn signals, and license plate lights. Now the problem is that one of the two license plate lights wont work. The weird thing is that both lights work just not at the same time. For example if the left light works then the right doesnt but if I switch the connection ( where the side plastics are, opposite side of the fuse box ) then the right one will turn on and the left turns off. So I dont think its my wiring since both lights work, just not at the same time. IDK whats wrong and its bugging me. If anyone can help, please do. Thanks.

Sounds like the grounds are reversed or something like that. Are these LEDs or incandescents? LEDs need the polarity correct and incandescents don't care (long as the body is not acting as the ground, hint has two wires).

However, if they are incandescents, you can pull the bulbs and measure the ground contact and see if it has a ground. They should both have the same ground and likely be tied together just to keep things simple.

If LEDs, use some jumper wires and confirm wire jacket colors are not mixed at the factory somehow. You know they both work (light) so write down the details and back track until you find the difference. Hint, there is an Anode and cathode, they connect to different sides of the LED. Study them and wire colors and see if the two are switched.

Some details would help.

Sounds like you have led license plate lights and one of them is reversed. That's why when you switch the polarity they change operation. Go to the junction where the both the lights are connected to each other and reverse one of them. Then try them and they should both light or not light depending on if you have them at correct polarity.....