TOPIC:

I have a 79 kz400 h1, with an electrical issue. None of the lights that should come on when the ignition is switched on and running come on (tail light, headlight, speed/tach lights). the brake light works when activated, as does the high beam. I have replaced the fuses and this does not change anything. I have tried to figure it out on the wiring diagram but have not been able to locate the culprit. Any suggestions?

Check all your connectors in the headlight bucket. If you have a multimeter, start checking continuity end-to-end.

Does your bike have a reserve lighting box? If it does, i would check that out too.

I suspect the issue isn't in the headlight shell connections since the red wire comes STRAIGHT off the igntion switch and goes back through the harness to the tail lamp to power the running light. If some stuff IS working when you turn the key on, I would suspect that the ignition switch itself may not be sending power on several of the wires and would check the main connector coming off the ignition switch. You can open this connector and turn the key on and see if there is voltage on the RED wire pin. The headlight probably doesn't have an ON/PO/OFF switch on the right switch gear. This means that there should be a BLUE wire associated pin on that same connector which probably goes back to a 10A fuse and then comes back as a BLUE sub-circuit that runs to your left switch gear where it powers your hi/lo beam on your headlight switch. I am not real positive about the wire color that feeds the blue circuit but look at a wiring diagram for your bike... it will likely have blue in it and it is the one that goes through a fuse and turns into the blue sub-circuit that feeds power to the hi/lo switch. The idiot lights likely have a small harness that gets its power from that same blue sub-circuit but again, you will need a wiring diagram to confirm this.