This material borrowed from Marcel Chichak; see more at http://www.starchak.ca/

In the United Kingdom, the British Standard BS-AU7 determines colour coding of automobile wiring.

Other colours are used, according to equipment specifications, e.g. light green, pink, slate. Handbooks
are usually printed in black and white only, so the cable colours are identified by a lettering code:
 

B	Black	P	Purple
U	Blue	G	Green
N	Brown	S	Slate
R	Red	W	White

When a cable has a base colour and a second colour trace the code is shown as two letters; for example:
WG = White with green trace
 

Main	Tracer	Destination
Black		All earth connections
Black	Blue	Tachometer generator to tachometer
Black	Brown	Tachometer generator to tachometer
Black	Green	Screenwiper switch to screenwiper (single speed) relay to radiator fan motor
Black	L. Green	Vacuum brake switch to warning light and/or buzzer
Black	Orange	Radiator fan motor to thermal switch
Black	Pink
Black	Purple
Black	Red	Electric speedometer
Black	Slate
Black	White	Brake fluid level warning light to switch and handbrake switch
Black	Yellow	Electric speedometer
Blue		Lighting switch (head) to dipper switch
Blue	Black
Blue	Brown
Blue	Green
Blue	L. Green	Screenwiper motor to switch
Blue	Orange
Blue	Pink	Headlamp dip beam fuse to left hand headlamp (when independently fused)
Blue	Purple
Blue	Red	Dipper switch to headlamp dip beam. Headlamp dip beam fuse to right-hand headlamp (when independently fused)
Blue	Slate	Headlamp main beam fuse to left hand headlamp or inboard headlamps (when independently fused)
Blue	White	Dipper switch to main beam (subsidiary circuit – headlamp flasher relay to headlamp). Headlamp main beam fuse to right-hand headlamp (when independently fused). Headlamp main beam fuse to outboard headlamps (when outboard headlamps independently fused). Dipper switch to main beam warning light
Blue	Yellow	Long range driving switch to lamp.
Brown		Main battery feed
Brown	Black	Alternator warning light, negative side
Brown	Blue	Control box (compensated voltage control only) to ignition and ignition switch, e.g. wipers, flashers, etc lighting switch (feed)
Brown	Green	Dynamo ‘F’ to control box ‘F’ Alternator field ‘F’ to control box ‘F’
Brown	L. Green	Screenwiper motor to switch
Brown	Orange
Brown	Pink
Brown	Purple	Alternator regulator feed
Brown	Red	Compression ignition starting aid to switch. Main battery feed to double-pole ignition switch (a.c. alt. system)
Brown	Slate
Brown	White	Ammeter to control box. Ammeter to main alternator terminal
Brown	Yellow	Dynamo ‘D’ to control box ‘D’and ignition warning light. Alternator neutral point
Green		Accessories fused via ignition switch (subsidiary circuit fuse A4 to hazard switch (terminal 6))
Green	Black	Fuel gauge to fuel tank unit or changeover switch
Green	Blue	Water temperature gauge to temperature unit
Green	Brown	Reverse lamp to switch
Green	L. green	Hazard flasher unit to hazard pilot lamp
Green	Orange	Low fuel level warning light
Green	Pink	Choke solenoid to choke switch (when fused)
Green	Purple	Stop lamps to stop lamp switch
Green	Red	Left-hand flasher lamps
Green	Slate	Heater motor to switch (or to fast)(on 2-speed motor)
Green	White	Right-hand flasher lamps
Green	Yellow	Heater motor to switch, single speed (or to ‘slow’ on two-speed motor)
L. Green		Instrument voltage stabilizer to instruments
L. Green	Black	Screen jet switch to screen jet motor
L. Green	Blue	Flasher switch to left-hand flasher warning light
L. Green	Brown	Flasher switch to flasher unit ‘L’
L. Green	Green
L. Green	Orange
L. Green	Pink	Flasher unit ‘L’ to emergency switch (simultaneous flashing)
L. Green	Purple	Flasher unit ‘F’ to flasher warning light
L. Green	Red	Fuel tank changeover switch to right-hand tank unit
L. Green	Slate	Fuel tank changeover switch to left-hand tank unit
L. Green	White
L. Green	Yellow	Flasher switch to right-hand flasher warning light
Purple		Accessories fused direct from battery
Purple	Black	Horn or horn relay to horn push
Purple	Blue
Purple	Brown	Horn fuse to horn relay (when horn is fused separately)
Purple	Green
Purple	L. Green
Purple	Orange	Aerial lift motor switch DOWN
Purple	Pink
Purple	Red	Boot light switch to boot light
Purple	Slate	Aerial lift motor to switch UP
Purple	White	Interior light to switch (subsidiary circuit—door safety lights to switch )
Purple	Yellow	Horn to horn relay
Red		Side and tail lamp feed
Red	Black	Parking switch to left-hand side lamp
Red	Blue
Red	Brown	Variable intensity panel lights (when used in addition to normal panel lights)
Red	Green	Lighting switch to side and tail lamp fuse (when fused)
Red	L. Green	Screenwiper motor to switch
Red	Orange	Parking light switch to right-hand sidelamp
Red	Pink
Red	Purple	Map light switch to map light
Red	Slate
Red	White	Panel light switch to panel lights
Red	Yellow	Fog lamp switch to fog lamp
Slate		Window lift
Slate	Black	Window lift
Slate	Blue	Window lift
Slate	Brown	Window lift
Slate	Green	Window lift
Slate	L. Green	Window lift
Slate	Orange	Window lift
Slate	Pink	Window lift
Slate	Purple	Window lift
Slate	Red	Window lift
Slate	White	Window lift
Slate	Yellow	Window lift
White		Ignition control circuit (unfused) (ignition switch to ballast resistor)
White	Black	Ignition coil CB to distributor contact breaker. Rear heated window to switch or fuse TAC ignition
White	Blue	Choke switch to choke solenoid (unfused). Rear heater fuse unit to switch. Electronic ignition TAC ignition unit to resistance.
White	Brown	Oil pressure switch to warning light or gauge
White	Green	Fuel pump No. 2 or left-hand to change-over switch
White	L. Green	Screenwiper motor to switch
White	Orange	Hazard warning feed (to switch)
White	Pink	Radio from ignition switch
White	Purple	Fuel pump No. 1 or right-hand to change-over switch
White	Red	Solenoid starter switch to starter push or inhibitor switch
White	Slate	Tachometer to ignition coil
White	Yellow	Starter inhibitor switch to starter push. Ballast resislor to coil. Starter solenoid to coil
Yellow		Overdrive
Yellow	Black
Yellow	Blue	Overdrive
Yellow	Brown	Overdrive
Yellow	Green	Overdrive
Yellow	L. Green	Screenwiper motor to switch
Yellow	Orange
Yellow	Pink
Yellow	Purple	Overdrive
Yellow	Red	Overdrive
Yellow	Slate
Yellow	White