From: Billo billo_at_unofficialbmw.com
Subject: Stereo Wiring
1980's era BMWs E23?, E24, E26, E28, E30
BETWEEN HEAD UNIT AND BOOSTER AMP
Yellow/Red - Left Front Channel
Yellow/Black - Left Rear Channel
Blue/Red - Right Front Channel
Blue/Black - Right Rear Channel
Yellow/Brown - Left Channel Ground at Amp End Only
Blue/Brown - Right Channel Ground at Amp End Only
Brown - All Channel Ground at Head End Only
(note that the all of the grounds are spliced together within the wiring harness - the
system uses a common ground between the head and the amplifer)
White - 12V Switched (to turn amplifier ON when head unit ON, also runs to power antenna)
BETWEEN AMP AND SPEAKERS
Pair: Black/White and Black/Brown - Right Rear Speakers
Pair: Grey/White and Grey/Brown - Right Front Speakers
Pair: Black/Red and Black/Purple - Left Rear Speakers
Pair: Grey/Red and Grey/Purple - Left Front Speakers
(note that the wires highlighted in red above all run to the crossover side of
the midrange drivers, you'll want to know this to keep all your speakers in
phase - make sure all of your speaker (+)s go to these wires)
(also note that the speaker circuits DO NOT use a common ground when they leave the
booster amp)
OTHER WIRES
Red/Black - 12V Battery Power (via 30 amp fuse in fusebox according to Bentley)
Brown - Power Ground
Also see this article
Dale's Wiring Non-Amplified E30 Stereo:
Note: '80's era cars had external amplifier and non-external amplifier systems. Be sure to
identify the type you have. All the premium stereo's had external amplifiers.
Speaker wiring goes from Radio to Fader control in dash, then to speakers.
Radio:
Brown: Ground
Purple/White: Accessory/Ignition 12v, main power
Red/White: Constant 12v?
Yellow: Constant 12v, use for memory
Green/Red: Dash lights 12v, varies with dash lights
White: power to antenna
Blue: Right+ (to fader)
Yellow: Left+ (to fader)
Blue/Brown: Right-
Yellow/Brown: Left-
Dash Fader Control to Speakers
Blue/Red: Right Front+
Blue/Black: Right Rear+
Yellow/Red: Left Front+
Yellow/Black: Left Rear+
Yellow/Brown: Left Channel Ground
Blue/Brown: Right Channel Ground
1990's era BMWs, E31, E32, E34, E36
Below is the 17 pin connection color coded wires on the newer models with the BMW Connector
X 18126
BMW CONNECTOR PIN# FUNCTION
FEMALE X18126
YELLOW/RE 1 LF CHANNEL +
BLUE/RED 2 RF CHANNEL +
YELLOW/BLACK 3 LR CHANNEL +
WHITE/BROWN 4 TELEPHONE MUTE
VIOLET/WHITE 5 HOT in ACCY, RUN and START
BLUE/BLACK 6 RR CHANNEL +
YELLOW 7 I-BUS CHANNEL +
YELLOW 7 EMPTY I-BUS
BROWN/ORANGE 8 LF CHANNEL -
RED/WHITE 9 HOT _at_ ALL TIMES
BLACK/WHITE 10 VECH./SPEED SIG.
BROWN/ORANGE 11 RF CHANNEL -
BROWN/ORANGE 12 LR CHANNEL -
GRAY/RED 13 ILLUMINATION
BROWN/ORANGE 14 RR CHANNEL -
BROWN 15 GROUND
WHITE 16 ANTENNA CONTROL
17 EMPTY