Friday, July 25, 2014.
I had stayed at the office till late, about ~9pm, and it was dark. I went to go home, tossed on my riding gear, and started my 1992 Honda Nighthawk. The headlight wasn’t working.
What was interesting is that neither the normal or the high-beam was working. Since I know that H4 bulbs (a common headlight bulb type) have two separate filaments, it should only lose low beam or high beam at once. Losing both at once is rare.
So to get home, I had to be rescued with some tools and wires. I simply ‘hot-wired’ the headlight buy running a wire right to the battery. I know it’s unsafe being unfused and all, but I had to make it home.
After taking a look at the wiring diagram below, I narrowed it down to a few things.
If you blow up the picture (I think you should be able to) you can trace the headlight to the dimmer switch (on the left handlebar) and curiously, the starter button (on the right handlebar). I knew the bulb was good, and tested wiring between the switches and the headlight. The wires were good, although at some point, someone had sliced into the headlamp wire, below.
So my best guess for the reason for this was a modulator (a dohickey that basically flashes the headlight, to make it supposedly easier to see). I fixed this by correctly splicing the wires using solder and heat shrink. Before, someone had just twisted the wires together and wrapped them with duct tape.
The solution ended up being that starter button – it needed some serious cleaning and a bit of grease.