79 GS425 no power to headlight

[Hokano12]

Headlight all of a sudden went out today. Every other light on the bike works but for some reason I’m getting no power to the headlight. I’ve checked the wiring diagram and cannot figure out where the headlight would be getting its power from. This is a gs425 so there is only 1 main fuse.

Like I said before, all other lights work, starter works, and bike runs but no headlight. Bench tested the headlight and it works. Tried tracking down with my volt meter but am getting stumped! Here’s a link to the diagram which is identical to the diagram I have in my Suzuki factory manual.

https://onedrive.live.com/?sc=documents&cid=2370B62DDF9F0C6B&id=2370B62DDF9F0C6B%211032&parId=2370B62DDF9F0C6B%211030&o=OneUp

Any help appreciated thank you!

[Brendan W]

Go to the headlight supply plug.
Check for continuity between the B/W pin and ground. If it's open you have a ground issue.
Check for 12V at the white pin on Lo beam and 12V at the yellow pin on Hi beam.
If there is supply to neither the move on to the dimmer switch and see if it is getting supply from the yellow input to the light switch itself.

[Hokano12]

Got it I’ll give it is a shot. Thank you!

[Hokano12]

Issue ended up being a bad jumper within the dimmer switch. Power comes in through the gray wire then a small yellow wire with white tracer brings power over to the white and yellow wires. There was voltage coming to the gray but not over to the yellow and white. Had to re solder the connection and now I have a light again! Thanks Brendan

[Brendan W]

Result
In fairness to the builders, they can't have imagined a forty year plus life for their products.