I’m struggling to find the issue with my brake lights. I bought the bike with a slew of electrical issues that I’ve slowly been diagnosing and fixing, but this one has had me stumped for a while. Both front and rear brake switch has continuity when connected, but when I press them down it does not make the lights any brighter. The previous owner installed LED tail lights along with new turn signals. The tail lights themselves are plus and play so no splicing was done, but the turn signals were spliced using electrical tape and twisting the wires. Is there any connection between the two for my brake lights not working?

 

Measure and test voltage on separate tail and brake light wires and verify they work properly. Tail-light wire should always be on and brake light wire has power only when you push pedal or pull lever.

Factory light goes to one bulb, but has 2 separate wires for 2 separate filaments inside bulb. Verify taillight actually has 2 separate LED elements, one for taillight and one for brake light function.


So you can have multiple errors:

1. brake light pedal/lever not sending power to brake-light wire at rear or...
2. LED taillight/brake doesn't have separate element for brake-light
3. brake-light wire not connected to LED brake-light.

Measure to find out which problem it is you're having. Unless you're Superman and can see electrons moving inside wires, there's absolutely ZERO way any human can just look at wires and determine its ability to conduct electricity. Luckily, we have instruments that can.

 

I got home and I hooked up my multimeter. The LEDs have two separate elements that are both lit up with just key on no brakes. I unplugged one light and tested each wire. Ground and one wire there was a constant 12 volts. Ground and the other and there was zero until brake was applied, then it would go to 4.6 volts. So does this mean my issue it the LEDs themselves are at fault?

 

Might have 2 different problems:

I would appear tail-light is mis-wired internally. Only ONE LED element should be lit with key ON. Then 2nd one should be OFF. And only turns on when powered by brake light wire.

By this, do you mean you unplugged tail/brake light and measured harness connector? If so, something’s wrong with your brake light wiring. It should be sending full-battery voltage when brake pedal/lever is on. Measure:

front-brake switch - measure by back-probing right-controls connector where it plugs into harness

1. Key ON, wht/grn power-input to switch, volts=??
2. Squeeze lever, grn/yel output power from switch, volts=??

rear-brake switch - measure where rear brake switch connects to harness

3. wht/grn power-input to switch, volts=??
4. Step on brake pedal, grn/yel output power from switch, volts=??

5. At tail/brake light 10p connector at rear, step on brake-pedal/squeeze lever, measure power at grn/yel wire terminal, volts =???


Post photos of how this light is plug-n-play. Does it plug into original harness 10p connector? or does it plug into original bulb-sockets?