I installed a custom tail light a few years ago. it has worked fine until recently when i tore my bike apart. I reconnected the same wires and now the running lights work but not the brake light. It has three wires black blue and red. i tried changing the wires around but to no avail. where else can i look to try to determine the problem. my bike is a 1996 FLSTN.

 

Not that familiar with Softtails... but on most, the wire from the light goes to the rear brake light switch and at the terminal is crimped together with the front brake light switch wire. Other side of the rear switch is incoming power. I would start there checking for voltage.

 

If you can pull it back off try testing it directly to a battery to see IF it's actually the problem. Then go from there. The red should be the run wire and the blue should light up the brake light. If it works then you can look elsewhere.