Psychophoria

I'm going to order one of those tonight. I powered everything back up after disconnecting the green aftermarket wire, but it sadly didn't affect anything. How does the fuse box look to you? Could that be causing the headlight problems? I rebuilt and cleaned the switches last night on the steering column as well. There was some buildup in some of the areas, which can be seen in the pics.

Two suspicious wires are connected to the back of the fuse box. I'm thinking maybe one is AC line and one is headlight line? Also found a melted portion of one of fuse sockets for park/tail fuse. I remember this from before from many years ago, the park/tail lights work. Despite that, I cleaned up the wire, recrimped it, and used a little hot glue to keep it from wiggling around. Would probably be best to replace this thing ASAP.

Okay, so... When the headlights are unplugged, voltage at the fusebox and the steering column switch is normal. When the headlights are plugged in, voltage drops to 0.04v. Edit: nevermind, now the voltage is back to 0.04v with headlights disconnected.

Working on the Z some more now.. I tested the passenger side headlight, powered it directly from the battery, and it works. I found a ground underneath the center console/dash and cleaned it. I'm wondering if that is the one that has been mentioned, it's in one of the pictures below. I cannot find any grounds near the horn. I think there were foglights at one point, so there are a few disconnected cables near the horn. There is one strange cable that ends abrupty in the front of the car, I followed it back to some sort of relay,you can see my finger touching where the wire plugs in. One more mystery wire, white wire that goes into the firewall not part of the main wiring harness. You can it with the blue tip in one of the images.

Thanks so much for such a detailed response, very helpful and informative. I've been trying to diagnose the issue for the last few hours, and wow, I'm getting even more confused. I started by checking the voltage in the fuse box, one cable of the multi meter on the metal fuse cap, the other end on a ground inside the car. Light L, off: 0v, on: 0.02v... Light R, off: 0v, on: 0.02v... Flasher L: 0.05v Flasher R: 0.07v... Flasher middle: 0v There are other fuses in there I tested the voltage off, the park tail for example, on: 11.46v, off: 12.35v The other fuses seem to have normal voltage, and as I mentioned, all the lights work beside the headlights and blinkers. At the right hand switch, with 4 solder points, I focused on the red & red + white wire. The red + white off: 12.36v and on: 11.78v. The red wire off: 0v and on: 0.05v.. BUT.. after a few minutes, I measure it again and while measuring the red wire goes from 0.05v to 11.78v. Up at the headlight plugs, one on each side of the horn, I measure the voltage by placing the multimeter leads onto the plug - one on the negative wire, one on the hi beam..then low beam. On the passenger side, low beam: 0.02v... high beam: 0.02v. Then measuring drivers side, I suddenly high beam: 11.65v... low beam: 11.70v. WHAT? I go back to the passenger side, and am suddenly getting voltage there too, despite the fact that a moment ago I wasn't. After this spectacle, I go back to the fuse box... I'm suddenly getting 11.78v on the Light L & R fuses, which confused me even further. I thought maybe the headlights would work, so I plugged them in, nothing. I've located two grounds in engine bay, and I cleaned them quite a bit. One comes off of the battery, to the fire wall. As the wiring harness leaves the firewall, heading towards the front of the vehicle, there is another ground that comes out, which I also cleaned. I attached a photo showing where those two are located. Other than that, I can't seem to find any other grounds in the engine bay. I've heard people talk about a ground in the steering column, is that just the ground directly under horn cap on the wheel?

After being apart for years, I'm finally reunited with my 73' 240z. Unfortunately, the headlights and blinkers are not functioning.. I'm hoping someone here can give me some pointers. The hazards work/flash, the running lights work, brake lights work. The headlights very briefly worked, and we're very feint. The drivers side went out completely, and the passenger side followed shortly after. At the headlight connector on the passenger side, I am reading 11.80v on the lowbeam lead and 11.65v on the high beam. The drivers side headlight connector doesn't read any volts at all. Both the right and left headlights read 0.02v at the fusebox, white the other fuses are reading normal 11.64v. Hm.. The switch with 4 wires, connected to the right side light knob of the steering column seems to be working. I am reading 11.65v from the red wire, 11.79v on the white/red wire when the switch is turned on. There is continuity between them when the switch is on. Nothing happens at all when the blinker knob is turned, although initially, the right turn signal indicator on the dash was constantly on despite the blinker itself not doing anything. The high beam seems to work though. If anyone has some pointers or ideas, I'd greatly appreciate it. When it comes to electronics, I'm a complete dummy. Really hoping to have her on the road again soon. Thanks all, and happy Thanksgiving!