Topic: headlight issue

[empiremica]

I have a '77 CB550 four SS. I replaced the OEM seat and taillight assembly just the other day with a caferacer-style seat that came with a new brake light and wiring. Since installing the new tail light, my headlight quit working. I traced the wires and did not find any loose connections or blown fuses. I tested the headlight and it works when hooked directly to the battery. Is there something I am missing? The new tail light came with a red, black, and green wires, which I am sure I hooked up right, but was there something in the original taillight assembly that completed a circuit or something? As always, I look forward to hearing everyones ideas. I am to the point where I am ready to direct wire the thing to a separate on/off switch if I can't work this out. It has got to be something obvious I am missing...

[TwoTired]

Check power to your headlight fuse...both terminal ends.

The fuse gets it's power from the starter button.  The button interrupts power to the headlight when pressed. (Or, if if fails.  Is there brake fluid getting to the switch?  Ever?)

Anyway, under the tank on the left side of the frame is where the control wires from/to the bar switches go.

Black ones are +12v with the key switch on.  Black/red is the one that powers the H/L fuse.

Head light wiring is not common with the tail light, apart from the key switch. (stock bike)

Cheers,

[333]

Have you checked the fuse?  If you upgraded the headlight to a halogen, it might be too much for the old fuse.  Then check the switch.  I think the 77 had  the power run through the key only, with the handlebar switch only goes hi/low.  All weak links, as we are talking about a 30 year old bike.