S30 JDM Tail Lamp Wiring
Here we will document the wiring changes needed to use JDM/Euro (amber bottom) tail lights in a US 240Z.
First lets define the US rear lighting, which is different than what Nissan used for the rest of the world. Here is a picture to illustrate which bulbs do what:
And for comparison, most of the rest of the world got lights configured like this:
The issue has always been that if you install the JDM lenses (amber bottom) with US wiring, you have both red and amber lights as both brake and flashers. Not optimal, to say the least. So what to do? Get a bit creative with wiring.
DISCLAIMER: Unlike every other mod I've done to my car, especially in the wiring, this mod requires you to cut and splice one or two wires (number depends on build date) in each tail light wiring harness (not the main harness, the small ones with the bulbs in it.) I did this on a spare pair of light harnesses, but if you don't have any spares, you'll need to hack up the ones your car came with. You have been warned.
The Wiring
here is a diagram of the stock US 240Z brake/rear turn wiring. This diagram is VERY simple, I've left out many details to promote clarity of purpose. I'm only showing the most pertinent items here.
So to make the US cars work like the JDM cars, you need to do a couple of things. First, snip the combined brake/flasher wires for all of the upper bulbs. They should be Green/Black on the right side of the car, and Green/Red on the left. A Series 1 car will have these wires to all four of the upper bulbs, but a later (1/71-on) 240Z will only have these wires to the outer bulbs, not the inner ones.
IMPORTANT: Do not cut the wire going to the lower, single filament bulb. You need to leave that one connected to the terminal in the wiring connector. Make certain that the cut ends from the connector are well insulated. Then attach a terminal to the snipped ends that you will use later.
Run a new wire from the front of the car near the steering column all the way to the rear of the car. This wire will be your new brake light circuit. At the front, disconnect the brake light output wire where it goes up to the turn signal switch and connect your new wire to the output wire of the brake light switch. (Two wires on the brake light switch, one is hot all the time. connect the new wire to the other one.) Don't plug anything into the wire going up to the turn signal switch. At the rear, this new wire needs to connect to the snipped wires on both sides of the car. Do that, and you're done. Here's another simple diagram to illustrate:
This wiring mod does not require amber lenses, you can still do it with all-red if you prefer this style of lighting, or just to be a touch different. (Side note: 260 and 280Zs all came wired this way, even though we still just got all-red lenses.)
Hybrid (or semi-divorced) system
The US cars got integrated (a.k.a. married) brake and turn signals. This was the norm for most American cars of that time. Cars from other countries generally got separate (a.k.a. divorced) brake and turn signal circuits. That was the norm in the rest of the world. But these days, many cars?both import and American?are coming with all-red rear lights, with a hybrid (or semi-divorced) system. These cars generally have two (or sometimes more) red bulbs on each side of the car.
In this system, at least one of those lights per side is the brake light only, and the other functions as an integrated brake/turn light. The advantage to this is that you have the maximum number of brake lights for warning following drivers. If you are simply stopping, all four light as brake lights. If you are slowing for a left turn, you have three brake and one flasher. Some examples are many newer Ford products, or the latest generation VW Jetta, among others.
The 240Z lights are well suited for this, and is the way I did my car as a safety measure. The later (1/71-on) 240Zs are especially good candidates for this, as they don't have as many brake lights in use as the Series 1 cars do. As with the stock US wiring, since the lower portion is often a brake light, this works properly only with all-red lenses.
The wiring for this mod is essentially the same as the JDM-mod, with one addition. At the front end of the new wire for the brake lights, tap a pigtail into the new wire and connect it to the wire from the turn signal switch that used to connect directly to the brake switch. Like so:
