S30 Wire Color Codes

Every wire in a 240Z, 260Z or 280Z harness is color coded, and the colors follow a system. Once you know it, a wiring diagram is much easier to read, and you can often tell what a wire does just by looking at it. This page explains the Nissan system using the factory service manual.

How the Code Works

Each wire is labeled with one or two letters in the wiring diagrams.
A single letter is a solid color wire. Main circuit wires are usually solid.
Two letters mean a wire with a stripe. The first letter is the base color and the second is the stripe. RW is a red wire with a white stripe; WR is a white wire with a red stripe. They are different wires.
The base color tells you which system the wire belongs to (see the table below). The stripe tells you which branch of that system it is.

Color Letters

Letter	Color
B	Black
W	White
R	Red
G	Green
Y	Yellow
L	Blue (L, not B, because B is black)
Lg	Light green
Br	Brown

Watch for L and Lg. Blue is always L, so LW is blue with a white stripe and BL would be black with a blue stripe.

Colors by System

The factory assigns a base color to each circuit system:

System	Base color	Stripes used
Starting and ignition	B (black)	W, Y, R
Charging	W (white)	B, R, L
Lighting	R (red)	W, B, G, Y, L
Signal (turn, stop, horn)	G (green)	W, B, R, Y, L
Instruments	Y (yellow)	W, B, G, R, L
Others	L (blue), Lg (light green)	W, R, Y
Ground	B (solid black)	None

From the 1975 280Z factory service manual, section BE, page BE-2.

Black is used twice. Solid black is ground, but black with a stripe (BW, BY and so on) is part of the starting and ignition system and is often hot. Don't assume every black wire is a ground.

Examples from the 1975 280Z

These wires appear in the factory circuit diagrams:

Code	Color	Where it goes
W	White	Battery feed from the starter motor terminal to the fusible link box
WR	White, red stripe	Main feed from the fusible link box to the ammeter shunt and on into the car
B	Black	Ground wires to the body earth points
BW	Black, white stripe	Ignition switch feed to the ignition unit and coil resistor
R	Red	Headlamp feed from the light switch through the headlamp fuses
RW / RB	Red, white or black stripe	Headlamp beam wires between the headlamps and the dimmer switch
GL	Green, blue stripe	Light switch feed to the instrument illumination
RL	Red, blue stripe	Dimmed illumination feed from the illumination resistor to the gauges

From the 1975 FSM, section BE (Fig. BE-16 and BE-22) and section EE. Colors can change between model years, so check your year's diagram before cutting anything.

Tips

Use your own year's diagram. The 240Z, 260Z and 280Z harnesses differ, and the 280Z changed again in 1977. The wiring diagrams are in the BE section of each factory service manual.
Old colors fade. White turns tan and stripes disappear under dirt and heat. Wipe the wire with a rag and a little cleaner, or look at a section that was protected inside the harness tape.
Check with a meter. Before you cut or splice, confirm what a wire does with a test light or meter. Previous owners didn't always follow the factory colors.
Match colors when you repair. If you add or replace a wire, use the same color, or at least the same base color, so the next person can still follow the diagram. Never use a smaller wire than the original.
Connector colors matter too. The big junction block connectors under the dash are colored as well (for example, the 1975 headlamp diagram lists C-1 green, C-3 black, C-4 brown).

Sources Used

1975 Datsun 280Z Factory Service Manual, section BE, page BE-2 (color table) and the circuit diagrams
1975 Datsun 280Z Factory Service Manual, section EE (ignition wire colors)