Brake lights not working. Relay failure?
 

I got another electrical problem :(
The tail light work but the brake light doesn't. Both the front and rear brake switches are ok and the blinkers also work. All fuses are good.
If I use a multimeter I get power at the lights connectors but the voltage reading doesn't change at all when braking. It's like the switches aren't working, but in fact they are.
From the wiring diagram it looks to me that the power line coming from the brake light switch runs through the blinkers relay. So could be a bad relay causing the malfunction in the brake light? But then why the blinkers work? What else could have gone bad between the lights and the switches?

Damn electrical problems, always a PITA to sort out. Please help!! Thanks!

Hi Killem'
Are you still using the regular bulbs? I know you had talked about switching to LEDs recently. It doesn’t look to me like the brake circuit runs through the flasher relay. The white/green tracer wire is the power feed for both brake and turn but it is in parallel, so they are separate. The green/ yellow tracer wire is the brake circuit wire at the bulbs. With the multimeter, + on the green/yellow and – on the green, you should have 0 volts, press a brake pedal, it should go to 12v ± a volt or two. The brown wire at the brake light bulbs is the +12v running lights (connecting brown + and green -).
I’m not sure what you mean by voltage change when applying the brakes. For both the brake and running lights, it would be all or nothing voltage. 0 or 12.

Have you check the bulb(s)?

Hey Greg!

Yeah I bought a LED tail light off ebay, it came wit no instructions so I'm trying to figure out how to wire it. But first I have to find out what's wrong with my tail light circuit.

The problem is that the voltage between the green/yellow and the green wires is stuck at 12V on both connectors and doesn't change at all if apply the brakes. Between brown and green wire the voltage is also 12V. Any ideas of what's going on?

Thanks a lot for your input!! :thumbsup:

Yeah, that ain't right, there shouldn't be any voltage between green/yellow and green with brakes off. My first thought would be the rear brake switch. It has an adjustment screw ring on it that may be set so the switch is too high. Underneath you'll see a spring that pulls on the switch to activate it. If the spring has too much tension, the switch may be stuck on. While I was monkeying around with mine the whole switch popped up out of the hole it rides in, my brake light then stayed on until I reset it.

I figured it out! The switches are ok, I had checked them with the MM before. But then you made me doubt again, so I went back took another look and realized that the cheap ass aftermarket front brake lever I installed a few days ago doesn't trigger the front switch all the times when it's released. That's why I was reading 12V no matter what. Dumbest thing ever .:bitchslap: :banghead:
Anyway, thanks a lot Greg for pointing me in the right direction:thumbsup: I'm gonna ride this weekend! :mrgreen:

Great! I have to laugh, I pulled my front brakes out from under the bench. Took a look at 'em and figured they wouldn't cause a problem.