Tail light acts funny when attached to fender

[Guest]

Wierdest thing - I'm installing a aftermarket tail light and it works fine when I wire it up, but as soon as I attach it to the fender the brake light will no longer function correctly. Once the tail light is attached, the light will stay on in the bright mode.

I thought that screwing the light into the fender would ground it... but there must be some sort of interference. Does anyone have a clue about where I should start?

Thanks!

[Tim Tom]

Wierdest thing - I'm installing a aftermarket tail light and it works fine when I wire it up, but as soon as I attach it to the fender the brake light will no longer function correctly. Once the tail light is attached, the light will stay on in the bright mode.

I thought that screwing the light into the fender would ground it... but there must be some sort of interference. Does anyone have a clue about where I should start?

Thanks!

Use some gasket material to make an 'isolating' gasket so it does not contact the metal fender at all. Then see if the problem persists.

[ChicagoBob]

Double-check the wiring and the ground on your fender. The wiring colors on some of the new aftermarket lights are not what you would think, such as having a black/white hot wire and a red or white ground. New turn signals are the same. China apparently uses different color codes than Japan. You probably just have yours wired incorrectly.

You should test the light from a 12V power source to determine the actual function of each wire.

[Redman]

Wires from Bike wiring harness:
White: Brake Lt
Brown: Tail Lt
Blk/Wht: Ground
Green: License Plate Lt


THe above is the color of wires from bike.
Do not just connect color for bike to color of new unit.
Need to check what is what in your aftermarket unit.

Start with the ground.


.