This covers most of the basic wire colors used on Airheads.  As the electronics got more complex, more combinations came into play so it's possible a few of the more obscure ones may see other uses.  Always double check factory wiring diagrams, and yes, even they can have a mistake or two.  PowerBoxer.de has a copy of the Haynes ones. And here's a link for more about Airhead relays and terminal designations.

!!! NOTE !!!

It was common practice to substitute a different wire color if the proper one was out of stock, and then "flag" it with the proper color(s).  As the flags' adhesive ages, it dries up and the flags often slide down the wire out of sight or fall off.  If you have an 'odd' wire, identify it through process of elimination by doing all others first, double checking with a volt/ohm meter, and then "re-flagging" it with the proper color. Better still, use heat shrink tubing of the proper color. ! ALSO ! Some books accidentally transpose numbers or letters on wiring diagrams (e.g. SW instead of WS, or two 86 terminals instead of a 85 and a 86).

2. Main Wire Colors

3. Lights' Wire Colors

4. Switch Wire Colors

Most common . . .


Still essentially universal among BMWs . . .


For Airheads . . .


Think you've got it? . . .

- - - - - - - TEXT ONLY VERSION - - - - - - -  

RT = Rot, red

GE = Gelb, yellow

GN = Grün, green

BL = Blau, blue

VI = Violet, purple

GR = Grau, grey

BR = Braun, brown

WS = Weiss, white

SW = Schwarz, black

xx/yy = xx wire's main color with yy stripe

MAIN Wire Colors

RT -- POSITIVE straight from battery, power to ignition key and starter relay

BR -- direct to GROUND

GN -- (+) power to most circuits

GR -- (+) power to PARK lights (head, tail, dash, ...)

GN/SW or GR/SW -- same as GN or GR but it's after the 8-amp FUSE

LIGHTS' Wire Colors

GE -- to LOW beam filament

WS -- to HIGH beam filament

GE/WS -- power to HI/LO switch

BL/RT -- LEFT turn signals

BL/SW -- RIGHT turn signals

GR/SW -- TAIL (as above)

GN/RT -- BRAKE light

SW/WS -- turn signal DASH INDICATOR

BL -- D+ from diode board and voltage regulator for GEN light

BR/SW -- NEU light 

BR/GN -- OIL light

BR/BL -- BREMSE / BRAKE FLUID light

WS -- HIGH BEAM indicator

GR/SW -- gauge illumination

SWITCH Wire Colors

BR/?? -- wire to SWITCH that completes path TO GROUND

BR/GE -- CLUTCH switch

BR/SW -- NEUTRAL switch

BR/GN -- OIL PRESSURE switch

BR/WS -- to HORNs with grounded bodies

BR/BL -- BRAKE FLUID switch

GN/BL -- engine CUT-OFF/KILL switch that supplies power to ignition coils

BL/GE -- to ground winding of STARTER RELAY

GN/VI -- trigger for HEADLIGHT RELAY

GN/GE -- TURN SIGNAL relay OUTPUT

Please email me (see "Contacts" under KS A/M) with any comments or suggestions. Thanks! --Joe