Headlight/Horn Problem

Hey guys,

Sometime last summer my horn stopped working, I didn't pay much attention to it as I rarely use it (typically the finger comes out not the horn...). However, at the end of last season I noticed my horn randomly started working again but my low beam headlight had stopped working, while my high beam still did. I left it as is form the winter, pulled it out today and now neither horn nor low beam work, high beam still works. I can only assume it is an electrical problem but I am not much of an electrician. Ideas about where to start to go about fixing this?

Thanks!

My guess on the horn is a poor electrical connection where the wires plug into the horn, and/or the horn has become corroded enough to not vibrate when you hit the horn button (it makes noise by vibrating, like home stereo speakers vibrating the speaker cone).
Sometime, rapping the horn while pushing the horn button will free it up if the horn is corroded.

For the low beam, I suspect either the headlight bulb has burned-out the low beam filament (new bulb would fix it), or the handlebar switch for hi/low beam is dirty and needs to be cleaned out.

Sounds like you'll have to temporarily repurpose that finger to trace little lines on a wiring diagram until you sort this out.

Assuming for a minute that both problems are related: The headlight and horn are on separately fused circuits, so it's probably unlikely that the problem is on the power supply side.  But both circuits are controlled by switches on the left handlebar, so they share a common connection to earth ground (battery negative terminal via connection to the frame) and they share a set of electrical connectors, which I believe are near the steering head.

My suggestions are:

1. Verify that the headlight fuse is good. (If either high or low beam beam works, this fuse is good.
   
2. Check electrical connector at the head light to verify it's clean, and free of corrosion and water etc.
   
3. Verify the horn fuse is good. (If the brake light, tail light, and license plate light works, this fuse is good.)
   
4. Locate both connectors (1 x 3 wires and 1 x 6 wires) that come from the switches and verify that they're clean, free of corrosion, and well-connected.
   
5. Trace the black ground wire shared by both circuits to it's termination at the frame and make sure it's a good connection too.
   

This wiring diagram should help.

Tear the switch apart and clean it with contact cleaner.
Last year my horn and signal lights stopped working, it was a dirty switch. The switch has drain holes in it, when I ride in dust the switch gets full of dust then when it gets wet it turns to mud. I tried filling the switch with dielecric grease but that made it worse as it held more dirt, clean and dry is the way to go with that switch. I blow the switch out with compressed air once and a while after washing the bike now.
My start button and kill switch acted up too form being dirty, clean them out while your at it.