In the United Kingdom the British Standard BS-AU7 determines colour coding of automobile wiring. Lucas use a 7 colour set in which plain colours - purple, green, blue, red, white, brown and green are supplemented by a further group using a base colour with a thin line trace of a different colour. Note that these are BS-AU7 colours, the MGB has some departures from this, indicated thus [ ].
Brown | main battery feed, unfused |
Purple | auxiliary devices not fed via the ignition switch, e.g. horn, interior light, fused |
White | base colour for ignition circuits, unfused |
Green | feeds to auxiliary devices controlled by the ignition switch, e.g. wipers, flashers, etc., fused |
Red | sidelights (parking lights), rear lights, instrument lights [and later American side-marker lights. Cars with the 4-fuse fusebox have red/green as the unfused colour to the instrument light rheostat or switch and the side/parking light fuses, fused red wires to the light units |
Blue | with white trace main beam headlamp, with red trace - dipped beam headlamp [plain blue is used from the main lighting switch to the dip-switch and to early American side-marker lights] |
Black | earth (ground) connections |
Handbooks are usually printed in black and white only, so the cable colours are identified by a lettering code, such as:
N | Brown | P | Purple | W | White | G | Green | R | Red | U | Blue | B | Black |
Other colours are used, according to equipment specifications:
S | Slate | LG | Light-Green | O | Orange | Y | Yellow | K | Pink |
When a wire has a base colour and a second trace colour the code is two letters, for example: WG = White with green tracer, RLG = Red with a Light Green tracer:
Destination | ||
All earth connections | ||
Tachometer generator to tachometer | ||
Tachometer generator to tachometer | ||
Screenwiper switch to screenwiper (single speed) relay to radiator fan motor | ||
Vacuum brake switch to warning light and/or buzzer | ||
Radiator fan motor to thermal switch | ||
Electric speedometer | ||
Brake fluid level warning light to switch and handbrake switch | ||
Electric speedometer | ||
Lighting switch (head) to dipper switch | ||
Screenwiper motor to switch | ||
Headlamp dip beam fuse to left hand headlamp when independently fused) | ||
Dipper switch to headlamp dip beam. Headlamp dip beam fuse to right-hand headlamp (when independently fused) | ||
Headlamp main beam fuse to left hand headlamp or inboard headlamps (when independently used) | ||
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 | ||
Long range driving switch to lamp. | ||
Main battery feed | ||
Alternator warning light, negative side | ||
Control box (compensated voltage control only) to ignition and ignition switch, e.g. wipers, flashers, etc. lighting switch (feed) | ||
Dynamo 'F' to control box 'F', Alternator field 'F' to control box 'F' | ||
Screenwiper motor to switch | ||
Alternator regulator feed | ||
Compression ignition starting aid to switch. Main battery feed to double pole ignition switch (ac alt. system) | ||
Ammeter to control box. Ammeter to main alternator terminal | ||
Dynamo 'D' to control box 'D' and ignition warning light. Alternator neutral point | ||
Accessories fused via ignition switch (subsidiary circuit fuse A4 to hazard switch (terminal 6)) | ||
Fuel gauge to fuel tank unit or changeover switch | ||
Water temperature gauge to temperature unit | ||
Reverse lamp to switch | ||
Hazard flasher unit to hazard pilot lamp | ||
Low fuel level warning light | ||
Choke solenoid to choke switch (when fused) | ||
Stop lamps to stop lamp switch | ||
Left-hand flasher lamps | ||
Heater motor to switch (or to fast)(on 2-speed motor) | ||
Right-hand flasher lamps | ||
Heater motor to switch, single speed (or to 'slow' on two-speed motor) | ||
Instrument voltage stabilizer to instruments | ||
Screen jet switch to screen jet motor | ||
Flasher switch to left-hand flasher warning light | ||
Flasher switch to flasher unit 'L' | ||
Flasher unit 'L' to emergency switch (simultaneous flashing) | ||
Flasher unit 'F' to flasher warning light | ||
Fuel tank changeover switch to right-hand tank unit | ||
Fuel tank changeover switch to left-hand tank unit | ||
Flasher switch to right-hand flasher warning light | ||
Accessories fused direct from battery | ||
Horn or horn relay to horn push | ||
Horn fuse to horn relay (when horn is fused separately) | ||
Aerial lift motor switch DOWN | ||
Boot light switch to boot light | ||
Aerial lift motor to switch UP | ||
Interior light to switch (subsidiary circuit door safety lights to switch) | ||
Horn to horn relay | ||
Side and tail lamp feed | ||
Parking switch to left-hand side lamp | ||
Variable intensity panel lights (when used in addition to normal panel lights) | ||
Lighting switch to side and tail lamp fuse (when fused) | ||
Screenwiper motor to switch | ||
Parking light switch to right-hand sidelamp | ||
Map light switch to map light | ||
Panel light switch to panel lights | ||
Fog lamp switch to fog lamp | ||
Window lift | ||
Window lift | ||
Window lift | ||
Window lift | ||
Window lift | ||
Window lift | ||
Window lift | ||
Window lift | ||
Window lift | ||
Window lift | ||
Window lift | ||
Window lift | ||
Ignition control circuit (unfused) (ignition switch to ballast resistor) | ||
Ignition coil CB to distributor contact breaker. Rear heated window to switch or fuse TAC ignition | ||
Choke switch to choke solenoid (unfused). Rear heater fuse unit to switch. Electronic ignition TAC ignition unit to resistance. | ||
Oil pressure switch to warning light or gauge | ||
Fuel pump No. 2 or left-hand to change-over switch | ||
Screenwiper motor to switch | ||
Hazard warning feed (to switch) | ||
Radio from ignition switch | ||
Fuel pump No. 1 or right-hand to change-over switch | ||
Solenoid starter switch to starter push or inhibitor switch | ||
Tachometer to ignition coil | ||
Starter inhibitor switch to starter push. Ballast resistor to coil. Starter solenoid to coil | ||
Overdrive | ||
Overdrive | ||
Overdrive | ||
Overdrive | ||
Screenwiper motor to switch | ||
Overdrive | ||
Overdrive | ||