1980 KZ750 LTD H1 No Running Lights

Hey all! First post on here, but longtime watcher of the forum.. So I've run into a wall with my own troubleshooting on this issue. Before I put the bike away for the winter last season it was having an intermittent issue where all my running lights - headlight (both hi/lo), running ambers up front, and taillight lo - all would just die away. Went over the fuses and those were intact and I saw voltage on my multi-meter. Attempted to trace out the wiring as best I could without really tearing into the thing but found no breaks or exposed copper. Replaced the ignition switch as a last ditch effort since one could be had from Z1 for a pretty decent price. No changes.

All four amber lights worked with the turn signal switch engages and the hazards as well. Brake light came on with the lever, but no headlight at all. I tossed in the towel and just said I'll deal with it come spring - and now here we are. I ended up getting it out today and to my surprise the 'headlight out' indicator light came on with no bulb in place. Before I winterized it this did not happen. I tossed a known-working H4 on it just to test and as soon as I turned it back on back to square one. I replaced the reserve lighting unit with a tested unit I got from a cycle shop off ebay that I've had good luck with in the past - no clue but it was had for $10. Issue still not solved.

So with all that I'm grasping at straws here. If I recall from my last troubleshooting efforts I wasn't consistently pulling voltage from the H4 socket, but I'll need to reconfirm this in the next few days. I'm wondering if ya'll have any other advice or common places of failure. Only other pertinent info is the guy I bought it from retrofitted in blade-type fuses instead of those barrel fellas. Prodded that a bit and got power over it so I'm fairly sure thats not causing it. All else fails I found a company out of Oregon that'll build a custom loom for like $250 since I know this is 40 year old wiring and it was a barn find when I got 'er.

Thanks for any insights!

Howdy. Do you have the Kawasaki manual for the motorcycle? There's a good pdf available w yellow/gold cover that has been linked multiple times. search KZR for 750Turbo.com. For wiring diagrams search mbsween KZ750L3.

First, I would charge the battery with a good motorcycle smart charger & do a load test to make certain the battery is good. easy.
I'm not familiar with the reserve lighting device, but the manual describes how it works, which might be useful.
There may also be a turn signal operating switch. not sure on the 1980 model.

Electrical stuff isn't my strong suit, but I would back-probe the ignition switch connector & use the wiring diagram to verify the voltages. Also, there's an ignition switch chart on the wiring diagram that you can use to check for continuity. unplug the connector for those tests.

If the ignition switch checks out & power is verified on both sides of all of the fuses, I guess I would open up the handlebar controls. corrosion or bad connections aren't uncommon. Before doing that, you could unplug the handlebar control connectors & check for continuity. My way is to just start checking stuff with a meter & I usually stumble upon the problem, hee. I use a VC97 digital multimeter & Ctek US 0.8 smart charger.

I have the same bike and have just made a new wiring harness. The amber running lights and dash lights run off the red/blue wire coming from the fuse box. This also goes to the ignition and is used to power the taillight - the red/blue and red (taillight) wires are bridged at the ignition switch when it is on. The ignition also provides power to the indicators/hazard lights (orange/green wire from the ignition). This would explain why the taillight and indicators etc. worked after swapping out the ignition. Not sure why the running light started working...
The power source for the headlight originally comes from the ignition, but it is the same power source as the horn, brake light, running lights etc. The power to the headlight/RLD splits off at the fuse box. This means that if everything else is working you need to check the following (in order):
- 10A fuse (blue/white to blue)
- continuity on the blue wire running from the fuse to the RLD
- continuity on the blue/orange or blue/yellow wire from the RLD to the left hand switch block (not sure which, one provides power to the headlight in normal conditions, the other is the backup in case a bulb blows)
- continuity on the red/yellow (low beam) and red/black (high beam) wires from the switch block to the headlight.

I agree with Martin in that you should check your battery and that it is probably a problem with the switch block. To confirm you could bypass the RLD (to rule it out as the source) by bridging the blue wire at the fuse to one of the wires going in to the switch block.