I spent last night working on my new garage sale Honda Aero. I was able to get it to run, but the starter, headlight, and dash lights were not working. I solved the starter issue pretty easily, dirty button plus improperly pinned connector on the wiring harness.

The lighting issues were a little more annoying. I quickly noticed after going over the wiring diagram, that all the lights were on the same circuit. I checked each wire for continuity first and didn’t find any issues. Next. I turned the bike on and tested for 12v at each light point, nothing, no voltage. I spent a few hours checking all the other pinouts in the wiring harness, but didn’t find any issue.

It was about this time that I pulled one of the dash lights and replaced with a similar one I had in the garage. Cranked the motor and it lit right up. Confused, I looked back over the wiring diagram and noticed that the whole lighting circuit runs AC :/


I’d been testing for DC...

So in the end it turned out that 4 lights on the same circuit all simultaneously burned out, that I’d shrugged off as impossible at the beginning of troubleshooting, was actually the problem.