Dear Tangled,
Minis, like most British cars, conform to a standard wire coding scheme so that wires can be identified when bundled together in a loom.
There are seven basic colours used:
Brown - Battery and alternator circuits
White - Ignition circuit
Blue - Headlight circuit
Red - Side and tail light circuit
Green - Auxiliary circuits fed through the ignition switch and protected by a fuse.
Purple - Circuits protected by a fuse but not fed through the ignition switch.
Black - Earth circuits.
Feed wires will carry the main colour only whereas switch wires will have the main colour with a second tracer colour to identify the sub-circuit. Where components are switched or controlled on the earth side, ie. the switch is in the return line, like the horn, the wire has a black tracer line.
