Morris Minor Owners Club

Hi just gleaned this from the net ,hope it's useful ,On old cars this needs to have a pinch of salt ready

LUCAS WIRING CODES

BROWN - Direct, un-switched, un-fused supply from the battery.
Usually wires to alternators, dynamos, control boxes and ignition
switches etc. Always live and often carrying heavy current.

YELLOW - Sometimes used as an alternative to Brown on older
cars. Also used on solenoids and overdrive switches.

PURPLE - Direct, un-switched but fused supply from the battery.

WHITE - Un-fused supply from the ignition switch to Fuel pump,
coil.

GREEN - Fused supply switched via the ignition switch. Indicators,
stop lights, instruments, wiper motor which only work when the
ignition is on

RED - The main colour for rear and side lights

BLACK - The usual colour for wires from components to earth
points on the body or chassis

BLUE - The main colour for front lights - Headlamps and
Spotlamps.

These refer to the main colour of the wires.

Many wires have a
second, thinner (tracer) colour.
This is used to identify the specific
purpose of the wire. E.g. Black/Green to Radiator fan motor

See Barry's diagram at the head of this section - it pretty much explains all, very clearly!

Yes I've seen it, I think my post supplements it very well.