Headlight trouble shooting

BustedNuckle

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Hey everyone, my headlight is not working..bulb is good. This bike is a recent purchase.. wondering does the bike need to be running to trouble shoot this? I think i remember reading that the headlight only comes on when started. Right now the bike does not start. I am getting full power to the signal lights, horn etc.. just not the headlight or neutral light. has a Boyer ignition. thanks everyone.
 
I believe the boys need year model and description if stock wiring. Perhaps Pictures also.
 
Pics, pics and more pics. Then year and aftermarket mods. And pics. Then what symptoms you see or hear. And of course, some pics.
 
Well, later models, starting in '78, had an auto-on headlight relay, but your '74 model wouldn't have that. It should just have a headlight on-off switch on the right handlebar control.

Finished.jpg
 
I am getting full power to the signal lights, horn etc.. just not the headlight or neutral light.
If the bike retains '74ish components and wiring scheme, the headlight should work w/o engine - the "safety relay" didn't incorporate the headlight circuit until '78 (when the off switch disappeared). Power comes from R/Y wire from key switch to blue wire on/off switch to dimmer switch to yellow and green.

The neutral light comes on with key switch (w/o engine) on all models, powered from the brown wire as are signals and horn.

Could be ground issue, but first check is to see if power on brown and red/yellow @ key switch then move through switches toward bulbs....
 
Thanks everyone for the quick replies.. i was going over some of the other posts and decided to pull the reserve lighting device and discovered PO had already done it but he did not connect the Blue/black wire to the Blue/yellow wire after unplugging it. As soon as i did this all was good and the headlight worked!! I also did the soldering of the relay which was a recommended thing but not sure if it was needed. I don't have stock gages or stock levers and it has a separate toggle switch hidden. As far as i can see the run/off/run switch on the right controls does not do anything... i am wondering if i might be able to use this switch for manually turning light on or off.
 

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If the right bar switch doesn't have a lights off switch and you have a Bl/Bk & Bl/Y wire present, it's not '74 wiring. IDK if the stock kill switch will like the amps pulled through the headlight circuit over time.

Where is your neutral light?
 
If the right bar switch doesn't have a lights off switch and you have a Bl/Bk & Bl/Y wire present, it's not '74 wiring. IDK if the stock kill switch will like the amps pulled through the headlight circuit over time.

Where is your neutral light?
The bike is reportedly a 74 motor and a 72 frame so PO may have just ordered a new wiring loom and modified it. The gauges are aftermarket and the neutral light is on the speedo.
 
So if I recognize the speedo in the pic (maybe) it may have a wire bundle that includes a green wire and a green/black stripe wire for neutral light. If so, green to brown from harness (or other normally powered, switched wire) and green/black to neutral switch from harness (light blue).
 
So if I recognize the speedo in the pic (maybe) it may have a wire bundle that includes a green wire and a green/black stripe wire for neutral light. If so, green to brown from harness (or other normally powered, switched wire) and green/black to neutral switch from harness (light blue).
perfect.. i will dig into it to see. Thx JP
 
It appears you have a newer right switch assembly without the headlight on-off switch. The kill switch has a R/W and brown wire running to it. On the stock bike, the brown is switched power from the key into the kill switch and the R/W carries that power out of it to the coils.

I'm not sure what that wire you soldered on is for, never heard of that mod before. I'm pretty sure that is the starter safety relay you were messing with there.
 
It appears you have a newer right switch assembly without the headlight on-off switch. The kill switch has a R/W and brown wire running to it. On the stock bike, the brown is switched power from the key into the kill switch and the R/W carries that power out of it to the coils.

I'm not sure what that wire you soldered on is for, never heard of that mod before. I'm pretty sure that is the starter safety relay you were messing with there.
I think that is to trick the bike into thinking it is already started so the light can come on, however i don't think i have to do that now that i removed the reserve lighting device and connected blue/black to blue/yellow.
 
You're missing the point - on your early model, the bike doesn't need to be running for the headlight to be turned on. It doesn't have the auto-on headlight relay the later models did. But yes, you do have to jumper the plug for the RLU if you remove it to restore power flow to the headlight.
 
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