Electrical standards - British Standard Vehical BS-AU7a
All Vehicles since the 80's have followed the BS-AU7a standard which recommends the colour code to be used on the insulation on the wires. This obviously makes identification of the various wires and circuits much easier.
| Colour | Abbreviation |
|---|---|
| Black | B |
Blue |
U |
| Brown | N |
| Green | G |
| Light Green | LG |
| Orange | |
| Purple | P |
| Red | R |
| White | W |
| Colour | Abbreviation | Circuit group |
|---|---|---|
| Black | B | All earth connections |
Blue |
U | Main beam lighting |
| Brown | N | Main feeds |
| Green | G | Acessories fused via ignition switch |
| Light Green | LG | Voltage stabilised supply to instruments |
| Orange | Wiper Circuits | |
| Purple | P | Accessories fed directly from battery |
| Red | R | All circuits fed from sidelight switch |
| White | W | Starter motor related |
| Colour | Description |
|---|---|
| Black/Brown | Tachometer generator to tachometer |
| Black/Blue | Tachometer generator to tachometer |
| Black/Red | Electric or electronic speedometer to sensor |
| Black/Purple | Temperature switch to warning light |
| Black/Green | Relay to radiator fan motor |
| Black/Light Green | Vacuum brake switch or brake diff. pressure valve to warning light and/or buzzer |
| Black/White | Brake fluid level warn light to switch and h'brake switch, or radio to speakers |
| Black/Yellow | Electric speedometer |
| Black/ Orange | Radiator fan motor to thermal switch |
| Colour | Description |
|---|---|
| Blue/Brown | Headlamp relay to headlamp fuse |
| Blue/Red | Dip switch to headlamp dip beam fuse. Fuse to right-hand dip headlamp |
| Blue/Light Green | Headlamp wiper motor to headlamp wash pump motor |
| Blue/White | a) Dip switch to headlamp main beam fuse |
| b) Headlamp flasher to main beam fuse | |
| c) Dip switch main beam warning light | |
| d) Dip switch to long-range driving light switch | |
| Black/Yellow | Long-range driving light switch to lamp |
| Blue/Black | Fuse to right-hand main headlamp |
| Blue/Pink | Fuse to left-hand dip headlamp |
| Blue/Slate | H'lamp main beam fuse to lh h'lamp or inboard h'lamps when independently fused |
| Blue/ Orange | Fuse to right-hand dip headlamp |
| Colour | Description |
|---|---|
| Green/Brown | Switch to reverse lamp |
| Green/Blue | Water temperature gauge to temperature unit |
| Green/Red | Direction indicator switch to left-hand flasher lamps |
| Green/Purple | Stop lamp switch to stop lamps, or stop lamp switch to lamp failure unit |
| Green/Light Green | Hazard flasher unit to hazard pilot lamp or lamp failure unit to stop lamp bulbs |
| Green/White | Direction indicator switch to right hand flasher lamps |
| Green/Yellow | Heater motor to switch single speed (or to 'slow' on two- or three-speed motor) |
| Green/Black | Fuel gauge to fuel tank unit or changeover switch or voltage stabilizer to tank units |
| Green/Pink | Fuse to flasher unit |
| Green/Slate | a) Heater motor to switch ('fast' on two- or three-speed motor) |
| b) Coolant level unit to warning light | |
| Green/Orange | Low fuel level switch to warning light |
| Colour | Description |
|---|---|
| Light Green/Brown | Flasher switch to flasher unit |
| Light Green/Blue | a) Flasher switch to left-hand flasher warning light |
| b) Coolant level sensor to control unit | |
| c) Test switch to coolant level control unit | |
| Light Green/Red | Fuel tank changeover switch to right-hand tank unit or entry and exit door closed switch to door actuator |
| Light Green/Purple | Flasher unit to flasher warning light |
| Light Green/Green | Start inhibitor relay to change speed switch; or switch to heater blower motor second speed on three-speed unit |
| Light Green/White | Low air pressure switch to buzzer and warning light Flasher switch to right-hand warning light; or |
| Light Green/Yellow | differential lock switch to differential lock warning light |
| Light Green/Black | Front screen jet switch to screen jet motor |
| Light Green/Slate | Fuel tank changeover switch to left-hand tank unit; or entry and exit door open switch to door actuator |
| Light Green/Orange | Rear window wash switch to wash pump; or cab lock-down switch to warning light |
| Colour | Description |
|---|---|
| Orange/Blue | Switch to front screen wiper motor first speed timer or intermittent unit |
| Orange/Green | Switch to front screen wiper motor second speed |
| Orange/Black | Switch to front screen wiper motor parking circuit, timer or intermittent unit |
| Orange/Purple | Timer or intermittent unit to motor parking circuit |
| Orange/White | Timer or intermittent unit to motor parking circuit |
| Orange/Yellow | Switch to headlamp or rear window wiper motor feed, timer or relay coil |
| Orange/Light Green | Switch to headlamp or rear window wiper motor parking circuit timer or relay coil |
| Orange/Pink | Timer or relay to headlamp or rear window wiper motor feed |
| Orange/Slate | Timer or relay to headlamp or rear window wiper motor parking circuit |
| Colour | Description |
|---|---|
| Purple/Brown | Horn fuse to horn relay when horn is fused separately |
| Purple/Blue | Fuse to heated rear window relay or switch and warning light |
| Purple/Red | Switches to map light, under bonnet light, glove box light and boot lamp when fed direct from battery fuse |
| Purple/Green | Fuse to hazard flasher |
| Purple/Light Green | Fuse to relay for screen demist |
| Purple/White | Interior lights to switch (subsidiary circuit door safety lights to switch) |
| Purple/Yellow | Horn to horn relay |
| Purple/Black | Horn to horn relay to horn push |
| Purple/Pink | Rear heated window to switch or relay |
| Purple/Slate | Aerial lift motor to switch up |
| Purple/Orange | Aerial lift motor to switch down |
| Colour | Description |
|---|---|
| Red/Brown | Rear fog guard switch to lamps |
| Red/Blue | Front fog lamp fuse to fog lamp switch |
| Red/Purple | Switches to map light, under bonnet light, glove box light and boot lamp when sidelamp circuit fed |
| Red/Green | Bulb failure unit to right-hand-side and rear lamps |
| Red/White | a) Sidelamp fuse to right-hand side and rear lamps |
| b) Sidelamp fuse to panel light rheostat | |
| c) Fuse to panel light switch or rheostat | |
| d) Fuse to fibre optic source | |
| Red/Yellow | Fog lamp switch to fog lamp or front fog fuse to fog lamps |
| Red/Black | Left-hand, sidelamp fuse to side and tail lamps and number plate illumination |
| Red/Pink | Sidelamp fuse to lighting relay |
| Red/Slate | Lamp failure unit to left-hand side and tail lamps |
| Red/Orange | Fusebox to rear fog guard switch |
| Red/Slate | Window lift main lead |
| Colour | Description |
|---|---|
| White/Brown | Oil pressure switch to warning light or gauge, or starter relay to oil pressure switch. Choke switch to choke solenoid (unfused) and/or choke to |
| White/Blue | switch to warning light, or electronic ignition distributor to drive resistor. Starter switch to starter solenoid or inhibitor switch |
| White/Red | or starter relay or ignition (start position) to bulb failure unit |
| White/Purple | Fuel pump no 1 or right-hand to changeover switch |
| White/Green | Fuel pump no 2 or left-hand to changeover switch. Start switch to starter interlock or oil pressure switch |
| White/ Light Green | to fuel pump or start inhibitor switch to starter relay or solenoid |
| White/Yellow | Ballast resistor to coil or starter solenoid to coil. Ignition coil contact breaker to distributor contact |
| White/Black | breaker, or distributor side of coil to voltage impulse tachometer |
| White/Pink | Ignition switch to radio fuse |
| White/Slate | Current tachometer to ignition coil |
| White/Orange | Hazard warning lead to switch |
| White/Yellow | a) Overdrive |
| b) Petrol injection | |
| c) Door Locks | |
| d) Gear selector switch to star |
| Colour | Description |
|---|---|
| Pink/White | Ballast terminal to ignition distributor |
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