Lucas Wiring Colour Codes

Based on a page by Chris Kantarjiev of The Dimebank Garage.

If the underside of your dashboard is a rat's nest, or if the wiring is all one colour, it may be time for a rewire. Or maybe you just want to add a couple of gauges such as a oil pressure or water temperature gauge. You know you should use the right colour wire, but who knows what's supposed to be red with a green stripe and what's supposed to be purple?

Take a look at the following charts and do the job properly!

The major colour groups are as follows:

MAIN	PURPOSE
Black	Earth / Ground
Brown	Hot (connected to power) all the time, unfused
Purple	Hot (connected to power) all the time, fused
White	Hot (connected to power) with ignition on, unfused
Green	Hot (connected to power) with ignition on, fused

Any manual should have a wiring diagram (Haynes is fine). You may find it helpful to enlarge the page to 11x17 with a photocopier and trace circuits with coloured pencils. Most electrical problems are caused by:

1. Bad ground connections
2. Corroded bullet connectors
3. Bodges by the DPO (Dumb Previous Owner)

I recommend replacing the fuse box outright if it looks old and corroded. It is an inexpensive part and will save you a lot of headaches down the road.

A pink eraser or 600 grit sandpaper can be used to clean contacts, and a smear of dialectric grease will help prevent future corrosion.

This is an extract from BS-AU7a 1983 Colour Code for Vehicle Wiring, from the British Standards Institution, 2 Park St., London W1A 2BS.

(Note that not all of these colour codes apply to the Morris Minor - this is the complete Lucas colour code list - for example, the wipers on cars up to 1980 (at least) are not on a separate fuse circuit, so they are not orange, but green. Check the schematic diagram in your workshop manual to be certain.)

MAIN	TRACER	PURPOSE
Black		All earth connections
Black	Brown	Tachometer generator to tachometer
Black	Blue	Tachometer generator to tachometer
Black	Red	Electric or electronic speedometer to sensor
Black	Purple	Tempreature switch to warning light
Black	Green	Relay to radiator fan motor
Black	Light Green	Vacuum brake switch or brake differential pressure valve to warning light and/or buzzer
Black	White	Brake fluid level warning light to switch and handbrake swith, or radio to speakers
Black	Yellow	Electric speedometer
Black	Orange	Radiator fan motor to thermal switch
MAIN	TRACER	PURPOSE
Blue		Lighting switch (head) to dip switch
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
Blue	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	Headlamp main beam fuse to left-hand headlamp or inboard headlamps when independently fused
Blue	Orange	Fushe to right-hand dip headlamp
MAIN	TRACER	PURPOSE
Brown		Main battery lead
Brown	Blue	Control box (compensated voltage control only) to ignition switch and lighting switch (feed)
Brown	Red	Compression ignition starting aid to switch Main battery feed to double pole ignition switch
Brown	Purple	Alternator regulator feed
Brown	Green	Dynamo 'F' to control box 'F' Alternator field 'F' to control box 'F'
Brown	White	Ammeter to control box Ammeter to main alternator terminal
Brown	Yellow	Alternator to 'no charge' warning light
Brown	Black	Alternator battery sensing lead
Brown	Slate	Starter relay contact to starter solenoid
Brown	Orange	Fuel shut-off (diesel stop)
MAIN	TRACER	PURPOSE
Green		Accessories fuesed via ignition switch
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 tow- 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
MAIN	TRACER	PURPOSE
Light Green		Instrument voltage stabilizer to instruments
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 coolan 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
Light Green	Yellow	Flasher switch to right-hand warning light; or 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
MAIN	TRACER	PURPOSE
Orange		Wiper circuits fused via ignition switch
Orange	Blue	Switch to front screen wiper motor first speed timer or intermittend unit
Orange	Green	Switch to front screen wiper motor second speed
Orange	Black	Switch to front screen wiper motor parking cicuit, 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
MAIN	TRACER	PURPOSE
Pink	White	Ballast terminal to ignition distributor
MAIN	TRACER	PURPOSE
Purple		Accessories fed direct from battery via fuse
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
MAIN	TRACER	PURPOSE
Red		Main feed to all circuits mastered by sidelamp switch
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 lef-hand side and tail lamps
Red	Orange	Fusebox to rear fog guard switch
MAIN	TRACER	PURPOSE
Slate		Window lift main lead
MAIN	TRACER	PURPOSE
White		Ignition switch or starter solenoid to ballast resistor
White	Brown	Oil pressure switch to warning light or gauge, or starter relay to oil pressure switch
White	Blue	Choke switch to choke solenoid (unfused) and/or choke to switch to warning light, or electronic ignition distributor to drive resistor
White	Red	Starter switch to starter solenoid or inhibitor switch 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
White	Light Green	Start switch to starter interlock or oil pressure switch to fuel pump or start inhibitor switch to starter relay or solenoid
White	Yellow	Ballast resistor to coil or starter solenoid to coil
White	Black	Ignition coil contact breaker to distributor contact 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
MAIN	TRACER	PURPOSE
Yellow		a) Overdrive b) Petrol injection c) Door locks d) Gear selector switch to start

You may want to check out the Monster Vendors list. for USA-based suppliers of bullet connectors, connector blocks, wire and complete wiring harnesses.

In the UK, check out the Morris Minor Centre (Birmingham).