SteveJ

And as far as "spoon feeding" goes, I've had to do more with people who had "engineer" titles. At least you found the source, and as you have learned the same lesson as many of us, it's frequently the last thing we f'd with.

I sent you my number in a PM a couple of weeks ago. Feel free to call to figure out how to get your wiring right.

There is neither a 400Z nor a Z35. It is a Nissan Z with a Z34 Series 2 chassis designation. Also the Z33 was 2003 MY to 2008. And the Nissan Z is 2023 MY.

We had a thread not too long ago about the 73 fuel gauge. Read through this for some ideas and watch the video of the bench test that is linked in the thread.

I don't know if this helps, but this is how it looks from behind the dash.

In Georgia, they think the signs identifying the freeway are the speed limits. If you think I-75 and I-85 are bad, you should try GA-400...

Actually it's not too important to find the exact place for the cross connection. The diode could be incorporated at the plug at the alternator. Of course, it might be easier just to replace the VR if it's bad, hence my suggestion of testing the resistance at the wires.

The problem is getting the connectors for the 280Z headlights. I could work around that in the 74-76, but even that involves backing pins out of the connectors between the dash harness and engine harness. See @Dave WM, even more reason to come up this way. There are even a couple of Publix around here for your wife.

What wattage headlights are you running? If the fuse was heating up enough to melt the solder (Yes, I've seen that happen.), a weaken connection would limit the amount of current that could flow. The good one might have partially failed, too, but not enough to take it out. You're also pushing more current through that circuit with the backfeeding of the other headlight. When you're doing the cleanup that @siteunseensuggested, don't forget to clean the contacts in the fuse box. And get off your duff and move up here so we can hang out.

Let's break things down. You said the car will shut off when you unplug the alternator. That means the alternator is backfeeding the ignition. That would be on the white/black wire attached to that plug. You may want to use an ohmmeter to measure the resistance between the white/black wire at the plug on the alternator and the black/white wire on the wiring harness. You'll need to backprobe the connector to get to the black/white wire. If the resistance is low, there is evidence of your problem. You will probably still need a diode to prevent the backfeed. Someone has definitely altered the wiring on your car. Nissan definitely NEVER used a wire nut on the Z wiring... (As an aside, I asked my wife if she could see what was wrong with the picture of the voltage regulator. She picked out the wire nut, too.) How long have you owned the car? It sounds like the IPO left you some surprises. What ignition system do you have on the car? I'm guessing it's not points. Anyway, you can wire the coil so that the tach doesn't work, and the car will run. Post some photos of the area around the ballast resistor and coil. If it's as I suspect, I have a video to help you sort that out. @Zed HeadThat was autocorrect on my phone. I'm back at my computer now, so improper words are my own ducking fault.

Let me guess...the car has an internally regulated alternator. It's backfeeding through the lamp wire to the ignition. MSA sells a plug that will take care of that.

One more thing, the temperature sender should connect to a yellow wire in an unmolested wiring harness.

I'm not sure what that thing is on the right because it's not a temperature sender. I usually just order the ones with the integrated threads myself. https://www.rockauto.com/en/moreinfo.php?pk=935425&cc=1209181&pt=4748&jsn=1308 At first I thought that might be the temperature switch, but it doesn't look like what MSA lists: https://www.thezstore.com/page/TZS/PROD/11-3122 By the way, the temperature sender should have a bullet connector like the one on the left (and the one I linked). The ports for the temperature sender and temperature switch are on the front of the housing below the radiator hose. The port on the side of the housing should be for the coolant tube for the carburetors.

I agree. It was @dutchzcarguy who mentioned the odometer. I mentioned the HUD because I like it since the speed is displayed in my line-of-sight as I'm driving. It's a reasonable price, too. https://www.amazon.com/gp/product/B07MCWG3JT

Not a Black Friday deal, but I found this universal drive 1/4 socket set comes in handy when removing the nuts from the studs on the intake and exhaust manifolds: https://www.amazon.com/gp/product/B0021I2KDO Note: I have a similar set with a 3/8 drive, but they can't fit into some of the nooks and crannies as easily as the 1/4 drive sockets.

The odometers still display in miles, but with the metric overlay you will know your speed, provided you have the correct speedometer cog for the transmission/differential/tires. I have been using a HUD GPS speedometer in my 260Z. Those will display in either metric or freedom units.

I'm not sure you have enough depth for a speaker install there. I did find this on Amazon: https://www.amazon.com/Herdio-Waterproof-Handling-Motorcycle-Surround/dp/B073XHZZ1W/ and https://www.amazon.com/Low-Profile-Waterproof-Marine-Speakers-Illuminating/dp/B07FMMVVZ6

At least you're willing to admit that you made a mistake.

To help you in your search, use the word "overlay" instead of sticker. Here is one I found: https://zcardepot.com/products/speedometer-tach-gauge-face-restoration-white-black-240z-260z-280z?variant=19283709034609&currency=USD&utm_source=google&utm_medium=cpc&utm_campaign=google+shopping&gclid=Cj0KCQiAkZKNBhDiARIsAPsk0Wj-xwSatWY9Q0yyr6v7xwer9s9BOk_xyavioLPbSOEquxZZbl5T2TMaAuwOEALw_wcB Search through the options to find what you want.

Your car has experienced the nefarious parking light fuse meltdown. You may want to consider the replacement fuse box from Motorsport Auto. https://www.thezstore.com/page/TZS/PROD/classic10a03/50-5010 The white/red wire going to the back of the fuse box is stock. The green wire with the forked lug is not stock.

Ugh. You're gonna make me take off the steering column cover on my car, aren't you? In the steering column, there is a ground wire that goes across under the column and plugs into a ground wire that runs back into the dash harness. If that wire is not securely plugged in, you won't have a ground for your headlights. By the way, let's get this sorted out first, and then we can turn our attention to the turn signals.

First, these are two COMPLETELY independent circuits. Headlights first. The readings you give are inconsistent. Are you measuring voltage to ground when measuring at the fuse box? If they are essentially 0 volts to ground there, you wouldn't have voltage at the headlight connector, provided you have the dash harness to engine harness connectors correct. Since they are color coded, I would expect they are hooked up properly. There is only one voltage source going to the passenger headlight socket. The other two wires go back to the combination switch which will ground one circuit (high beam or low beam) or the other. If the headlight switch is on when the circuit is not grounded, you could see voltage at all three points on the connector if the other side headlight is plugged in. Here's how the circuit flows: The white/red wire goes to the right hand switch. When the switch is on, there should be voltage on the red wire. The red wire goes to the fuse box and splits between the left and right headlight fuses. The right side fuse comes out as a red wire. The left side fuse comes out as a red/yellow wire. The wires go to the connector for the dash harness to engine harness and out to their respective headlights. With the headlight plugged in, the wiring path goes back through the red/black (low) and red/white (high) wires The red/black and red/white go through the engine harness to the dash harness and back to the left switch. The left switch will connect one of those two wires to ground. One of the first things to do is make sure you connected the ground wire at the steering column. A loose or missing ground will make your voltage reading wonky. The high beam indicator on the gauge goes from the right headlight fuse to the gauge and out as a red/white wire that joins up to the red/white wire that came back from the headlights. For the turn signals, if there is not enough current flowing through the old flasher relay, the light(s) connected on that circuit will tend to stay on. You'll see this if there LED bulbs with the old style flasher relay. The old flasher relays would heat up with enough current flow. This would cause the bimetal strip in the relay to bend away from the circuit. This would cause the lights to go off. Once the current stops flowing through the bimetal strip, it cools, and the strip goes back into place, completing the circuit again.

I'm thinking more like Memphis because of the heat. The track and People's Choice show were both way across town for that ZCON. For 2022 Barber is only 20 miles from the hotel, but Holy Cow, Talledega Gran Prix is an hour away. You can be sure that the wife will be following in her own air conditioned vehicle for the trip to ZCON.

The links are live for booking a hotel room for ZCON 2022. I got my reservations. http://zcon.org/conventions/2022/hotels/ By the way Buc-ee's fans, there is a Buc-ee's located 20 miles from the convention hotel.