I bought my 240z without a title. In Colorado, a non-titled vehicle requires an official State Patrol VIN inspection. Everything needed to drive on the street has to work, otherwise you're stuck with a "salvage" title. Getting the electrical sorted out was a priority... and a major headache.

Bad Wire Splice I'm pretty good with electrical systems but this car was a nightmare. Wiring diagrams back then were hand-drawn and not easily updated. I found various diagrams online but not all of the colors matched mine. Was it a '70, or a '71, or a California model with emissions or Canadian with an automatic transmission?

I traced things back and forth. I poked and prodded. One moment the headlights were dark but the horn worked, or the headlights worked but not the flashers, and so on. It drove me nuts. I ended up tearing everything out and started from scratch, which turned out to be the right choice because behind the dash was a failed factory splice that created the intermittent problem.

240z Wiring Diagram 240z Wiring Diagram Ace King's 240z Wiring Diagram Instead of copying the original Datsun design, I upgraded it to modern standards. I had to reverse-engineer the switches, the lights, the gauges and match the stock colors up with the new colors. I bought new OEM connectors, bulb sockets, relays, and lots of wire. It took more time than I'd feared, but now everything works. I'm a drafter by trade, so the new diagram is far better than Datsun ever dreamed.

Click on the upper image to see their diagram, or click on the lower image for a PDF of mine.

Wiring Diagram Here's the sketches I made of the gauges. Armed with a test light and a fair amount of patience, I figured out how each one worked. I even puzzled out the heater switch connections - something Nissan never showed on their diagrams.

The existing wires were crimped into the connectors and the new wires are on the other side. It worked pretty slick.

If you're looking for connectors, the absolutely best place I've found is Oregon Motorcycle Parts. They specialize in connectors for vintage Japanese motorcycles, which happen to be the same ones used by Datsun.

240z Headlights Here's how I modified the headlight-wiper switch. Each of the wires was labelled, then attached to the new connector. Hopefully I'll never have to remove them, but I'm ready if I do.

In the original design, power for the headlights went directly thru the switch. That's how all maunfacturers did it back them. The problem is that over time, the switch contacts and the connector pins slowly corroded, which created resistance. The result is heat, and with many cars it gets hot enough to melt the insulation around the connectors, and even the plastic around the fuses.

I took apart the mechanism and cleaned the corroded contacts. It shouldn't overheat again because all it does now is turn a little relay on or off. The relay itself takes power from the new fuse block and sends it directly to the headlights. The wires are large enough that I can upgrade to more powerful lights in the future.

I did the same modifications with the turn indicator and ignition switches. All nice and clean.

For the most part, the electrical portion of this project is done. Whew.

Other Upgrades:

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