Spent a few hours diagnosing an interesting problem on my 1976 cb750K6 today. Both front turn signals (the large “pancake” style) contain dual filament bulbs in the correct socket. Solid light blue and solid orange wires are the bright (+) feeds. The light blue with a white band, and orange with a blue band wires feed (+) to the lower intensity running lights. Both lamps are grounded internally and both stalks have a ground wire connected to the square washer under the fixing nut, inside the headlamp housing. Both turn signals work as they should.
The running lights are plugged into the corresponding, matching wires inside the headlamp housing and feed into the main harness. Note that on this model there is no light switch. The headlight and tail light come on with the key switch. The headlamp has the usual Hi-Lo switch on the left bar controls. Regardless of what I did, there is no power being fed to the front running lights.
So I pulled out my Factory Manual and traced the banded wires back from turnsignals. Sure enough, they plug into the main harness (just as I did). Follow those two feeds back through the harness and guess where they lead? NOWHERE. THEY JUST END. HOOKED UP TO NOTHING. WTF? Obviously plans or regulations changed? Complete mystery. Surely there is an explaination?
I made up a solid jumper harness and connected both running lights to the low beam feed. They shut off when running the high beam. They are working now, for the first time in 47 years. Very strange…..