Joseph Lucas: The Prince of Darkness. - the TR Register Groups ...
Joseph Lucas: The Prince of Darkness. - the TR Register Groups ...
Joseph Lucas: The Prince of Darkness. - the TR Register Groups ...
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http://www.peterrenn.co.uk/archive4.html<br />
Features Archive:<br />
<strong>Joseph</strong> <strong>Lucas</strong>: <strong>The</strong> <strong>Prince</strong> <strong>of</strong> <strong>Darkness</strong>.<br />
(1890s translucent overalls whilst undeniably stylish proved sadly impractical..)<br />
So <strong>the</strong>re you are, grubby Haynes Manual in one hand, circuit tester in <strong>the</strong> o<strong>the</strong>r trying to work<br />
out why <strong>the</strong> lights/horn/wipers/cigarette lighter/clock etc. won't work, (apart from <strong>the</strong> fact that it<br />
has '<strong>Lucas</strong>' stamped on it that is.) Tracing <strong>the</strong> circuit usually works eventually but <strong>of</strong>ten you<br />
find yourself with several loose wires and no clues as to where <strong>the</strong>y go, in which case you<br />
need a clue or two.<br />
<strong>The</strong>re is a British Standard for vehicle wiring number BS-AU7a which defines <strong>the</strong> colours and<br />
allows you to trace where <strong>the</strong> wires should go from first principles ra<strong>the</strong>r than a diagram. It<br />
also allows accessories such as electric fans to be added with <strong>the</strong> correct coloured wires<br />
which assists later diagnosis enormously.<br />
None <strong>of</strong> this helps <strong>the</strong> fact that <strong>the</strong> things on <strong>the</strong> ends <strong>of</strong> <strong>the</strong> wires are usually made by <strong>Lucas</strong><br />
and are <strong>the</strong>refore <strong>of</strong> er.. variable quality! I'm particularly fond <strong>of</strong> a description <strong>of</strong> an E-type<br />
Jaguar's headlamp switch as having" three positions: DIM, FLICKER and OFF.<br />
Anyway, that's enough potentially libellous comments (I'm sure all <strong>Lucas</strong> products are simply<br />
fab nowadays and <strong>the</strong> repro stuff is only crap because it is so au<strong>the</strong>ntic :) This info should not<br />
only allow you to trace original wires but also to use <strong>the</strong> correct colours when adding<br />
additional equipment like spotlights, ejector seats or whatever.<br />
Firstly <strong>the</strong> basics- What <strong>The</strong> Colours Mean:<br />
BROWN is for direct, unswitched, unfused supply from <strong>the</strong> battery. Seen on wires to<br />
alternators, dynamos, control boxes and ignition switches etc. Always live and <strong>of</strong>ten carrying<br />
heavy current.<br />
YELLOW sometimes used as an alternative to brown on older cars. Also used on solenoids<br />
and overdrive switches.
http://www.peterrenn.co.uk/archive4.html<br />
PURPLE Direct, unswitched but fused supply from <strong>the</strong> battery. On older cars with no purple<br />
wires, brown wires with a secondary tracer colour are used.<br />
WHITE Unfused supply from <strong>the</strong> ignition switch.<br />
GREEN Fused supply switched via <strong>the</strong> ignition switch. Used for things like <strong>the</strong> wiper motor,<br />
indicators and brake lights which only work when <strong>the</strong> ignition is on.<br />
BLUE <strong>The</strong> main colour for front lights- headlamps and spotlamps.<br />
RED <strong>The</strong> main colour for rear and side lights.<br />
BLACK Usual colour for wires from components to earth points on <strong>the</strong> body.<br />
<strong>The</strong>se refer to <strong>the</strong> main colour <strong>of</strong> <strong>the</strong> wire. <strong>The</strong> second tracer colour which is on many wires is<br />
<strong>the</strong> thinner line and is used to identify <strong>the</strong> wire. <strong>The</strong>re is a certain amount <strong>of</strong> logic to <strong>the</strong>m too<br />
as you will see.<br />
Below is <strong>the</strong> colour code table for BS-AU7a which was amended in <strong>the</strong> 'eighties so <strong>the</strong>re will<br />
be a few variations on our '50s to '70s cars..<br />
Main colour is given first , tracer second<br />
MAINLY BLACK WIRES<br />
Black<br />
Black/ Brown<br />
Black/ Blue<br />
Black/ Red<br />
Black/ Purple<br />
Black/ Green<br />
Black/ Light Green<br />
Black/ White<br />
Black/ Yellow<br />
Black/ Orange<br />
All earth connections<br />
Tachometer generator to tachometer<br />
Tachometer generator to tachometer<br />
Electric or electronic speedometer to sensor<br />
Temperature switch to warning light<br />
Relay to radiator fan motor<br />
Vacuum brake switch or brake differential pressure valve to warning light<br />
and/or buzzer<br />
Brake fluid level warning light to switch and handbrake switch, or radio to<br />
speakers<br />
Electric speedometer<br />
Radiator fan motor to <strong>the</strong>rmal switch<br />
MAINLY BLUE WIRES<br />
Blue<br />
Blue/ Brown<br />
Blue/ Red<br />
Blue/ Light green<br />
Blue/ White<br />
Blue/ Yellow<br />
Blue/ Black<br />
Blue/ Pink<br />
Blue/ Slate<br />
Blue/ Orange<br />
Lighting switch (head) to dip switch<br />
Headlamp relay to headlamp fuse<br />
Dip switch to headlamp dip beam fuse. Fuse to right-hand dip headlamp<br />
Headlamp wiper motor to headlamp wash pump motor<br />
a) Dip switch to headlamp main beam fuse<br />
b) Headlamp flasher to main beam fuse<br />
c) Dip switch main beam warning light<br />
d) Dip switch to long-range driving light switch<br />
Long-range driving light switch to lamp<br />
Fuse to right-hand main headlamp<br />
Fuse to left-hand dip headlamp<br />
Headlamp main beam fuse to left-hand headlamp or inboard headlamps when<br />
independently fused<br />
Fuse to right-hand dip headlamp
http://www.peterrenn.co.uk/archive4.html<br />
MAINLY BROWN WIRES<br />
Brown<br />
Brown/ Blue<br />
Brown/ Red<br />
Brown/ Purple<br />
Brown/ Green<br />
Brown/ White<br />
Brown/ Yellow<br />
Brown/ Black<br />
Brown/ Slate<br />
Brown/ Orange<br />
Main battery lead<br />
Control box (compensated voltage control only) to ignition switch and lighting<br />
switch (feed)<br />
Compression ignition starting aid to switch. Main battery feed to double pole<br />
ignition switch<br />
Alternator regulator feed<br />
Dynamo 'F' to control box 'F' Alternator field 'F' to control box 'F'<br />
Ammeter to control box. Ammeter to main alternator terminal<br />
Alternator to 'no charge' warning light<br />
Alternator battery sensing lead<br />
Starter relay contact to starter solenoid<br />
Fuel shut-<strong>of</strong>f (diesel stop)<br />
MAINLY GREEN WIRES<br />
Green<br />
Green/Brown<br />
Green/ Blue<br />
Green/ Red<br />
Green/ Purple<br />
Green/ Light green<br />
Green/ White<br />
Green/ Yellow<br />
Green/ Black<br />
Green/ Pink<br />
Green/ Slate<br />
Green/ Orange<br />
Light green<br />
Light green/ Brown<br />
Light green/ Blue<br />
Light green/ Red<br />
Light green/ Purple<br />
Light green/ Green<br />
Light green/ White<br />
Light green/ Yellow<br />
Light green /Black<br />
Light green /Slate<br />
Light green/ Orange<br />
Accessories fused via ignition switch<br />
Switch to reverse lamp<br />
Water temperature gauge to temperature unit<br />
Direction indicator switch to left-hand flasher lamps<br />
Stop lamp switch to stop lamps, or stop lamp switch to lamp failure unit<br />
Hazard flasher unit to hazard pilot lamp or lamp failure unit to stop lamp bulbs<br />
Direction indicator switch to right hand flasher lamps<br />
Heater motor to switch single speed (or to 'slow' on two- or three-speed<br />
motor)<br />
Fuel gauge to fuel tank unit or changeover switch or voltage stabilizer to tank<br />
units<br />
Fuse to flasher unit<br />
a) Heater motor to switch ('fast' on two- or three-speed motor)<br />
b) Coolant level unit to warning light<br />
Low fuel level switch to warning light<br />
Instrument voltage stabilizer to instruments<br />
Flasher switch to flasher unit<br />
a) Flasher switch to left-hand flasher warning light<br />
b) Coolant level sensor to control unit<br />
c) Test switch to coolant level control unit<br />
Fuel tank changeover switch to right-hand tank unit or entry and exit door<br />
closed switch to door actuator<br />
Flasher unit to flasher warning light<br />
Start inhibitor relay to change speed switch; or switch to heater blower motor<br />
second speed on three-speed unit<br />
Low air pressure switch to buzzer and warning light Flasher switch to righthand<br />
warning light; or<br />
differential lock switch to differential lock warning light<br />
Front screen jet switch to screen jet motor<br />
Fuel tank changeover switch to left-hand tank unit; or entry and exit door open<br />
switch to door actuator<br />
Rear window wash switch to wash pump; or cab lock-down switch to warning<br />
light
http://www.peterrenn.co.uk/archive4.html<br />
MAINLY ORANGE WIRES<br />
Orange<br />
Orange/ Blue<br />
Orange/ Green<br />
Orange/ Black<br />
Orange/ Purple<br />
Orange/ White<br />
Orange/ Yellow<br />
Orange/Light green<br />
Orange/ Pink<br />
Orange/ Slate<br />
Wiper circuits fused via ignition switch<br />
Switch to front screen wiper motor first speed timer or intermittent unit<br />
Switch to front screen wiper motor second speed<br />
Switch to front screen wiper motor parking circuit, timer or intermittent unit<br />
Timer or intermittent unit to motor parking circuit<br />
Timer or intermittent unit to motor parking circuit<br />
Switch to headlamp or rear window wiper motor feed, timer or relay coil<br />
Switch to headlamp or rear window wiper motor parking circuit timer or relay<br />
coil<br />
Timer or relay to headlamp or rear window wiper motor feed<br />
Timer or relay to headlamp or rear window wiper motor parking circuit<br />
MAINLY PURPLE WIRES<br />
Purple<br />
Purple/ Brown<br />
Purple/ Blue<br />
Purple/ Red<br />
Purple/ Green<br />
Purple/ Light green<br />
Purple/ White<br />
Purple/ Yellow<br />
Purple/ Black<br />
Purple/ Pink<br />
Purple/ Slate<br />
Purple/ Orange<br />
Accessories fed direct from battery via fuse<br />
Horn fuse to horn relay when horn is fused separately<br />
Fuse to heated rear window relay or switch and warning light<br />
Switches to map light, under bonnet light, glove box light and boot lamp when<br />
fed direct from battery fuse<br />
Fuse to hazard flasher<br />
Fuse to relay for screen demist<br />
Interior lights to switch (subsidiary circuit door safety lights to switch)<br />
Horn to horn relay<br />
Horn to horn relay to horn push<br />
Rear heated window to switch or relay<br />
Aerial lift motor to switch up<br />
Aerial lift motor to switch down<br />
MAINLY RED WIRES<br />
Red<br />
Red/ Brown<br />
Red/ Blue<br />
Red/ Purple<br />
Red/ Green<br />
Red/ White<br />
Red / Yellow<br />
Red/ Black<br />
Red/ Pink<br />
Red/ Slate<br />
Red/ Orange<br />
Red/ Slate<br />
Main feed to all circuits mastered by sidelamp switch<br />
Rear fog guard switch to lamps<br />
Front fog lamp fuse to fog lamp switch<br />
Switches to map light, under bonnet light, glove box light and boot lamp when<br />
sidelamp circuit fed<br />
Bulb failure unit to right-hand-side and rear lamps<br />
a) Sidelamp fuse to right-hand side and rear lamps<br />
b) Sidelamp fuse to panel light rheostat<br />
c) Fuse to panel light switch or rheostat<br />
d) Fuse to fibre optic source<br />
Fog lamp switch to fog lamp or front fog fuse to fog lamps<br />
Left-hand, sidelamp fuse to side and tail lamps and number plate illumination<br />
Sidelamp fuse to lighting relay<br />
Lamp failure unit to left-hand side and tail lamps<br />
Fusebox to rear fog guard switch<br />
Window lift main lead
http://www.peterrenn.co.uk/archive4.html<br />
MAINLY WHITE WIRES<br />
White<br />
White/ Brown<br />
White/ Blue<br />
White/ Red<br />
White/ Purple<br />
White/ Green<br />
White/ Light green<br />
White/ Yellow<br />
White/ Black<br />
White/ Pink<br />
White/ Slate<br />
White/ Orange<br />
White/Yellow<br />
(or just plain yellow)<br />
Ignition switch or starter solenoid to ballast resistor<br />
Oil pressure switch to warning light or gauge, or starter relay to oil pressure<br />
switch. Choke switch to choke solenoid (unfused) and/or choke to<br />
switch to warning light, or electronic ignition distributor to drive resistor.<br />
Starter switch to starter solenoid or inhibitor switch<br />
or starter relay or ignition (start position) to bulb failure unit<br />
Fuel pump no 1 or right-hand to changeover switch<br />
Fuel pump no 2 or left-hand to changeover switch. Start switch to starter<br />
interlock or oil pressure switch<br />
to fuel pump or start inhibitor switch to starter relay or solenoid<br />
Ballast resistor to coil or starter solenoid to coil. Ignition coil contact breaker to<br />
distributor contact<br />
breaker, or distributor side <strong>of</strong> coil to voltage impulse tachometer<br />
Ignition switch to radio fuse<br />
Current tachometer to ignition coil<br />
Hazard warning lead to switch<br />
a) Overdrive<br />
b) Petrol injection<br />
c) Door locks<br />
d) Gear selector switch to start<br />
YELLOW WIRES<br />
Yellow<br />
(or yellow/white)<br />
a) Overdrive<br />
b) Petrol injection<br />
c) Door locks<br />
d) Gear selector switch to start<br />
PINK WIRE(!)<br />
Pink/ white<br />
Ballast terminal to ignition distributor<br />
That's all folks. <strong>The</strong> usual disclaimer applies., ie that This is correct to <strong>the</strong><br />
best <strong>of</strong> my knowledge but you use this information at your own risk. So don't<br />
sue me if you blow your alternator or fry all your relays...
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