BMW Motorcycles, cars, and most all European
Vehicles:
Metric & American Wires,
Colors, Bosch Codes
©
copyright 2012, R. Fleischer
wires&codes.htm-26
The wiring diagrams, sometimes called Electrical Schematic Diagrams, for your airhead,
will usually show the wire insulation color
and the cross-sectional size (in mm) of the conductor. American wire gauge sizes are seldom used in vehicles in odd
number sizes. American wire sizes are specified in GAUGE (ga), a different
system of measurement. If you are replacing or installing wiring, use the
same equivalent or next lower ga number (next larger size) as shown.
For other than the factory specified wire size and usage, you
should know that the larger the expected current flow, the larger the conductor needs to be. The longer the run of wire, the larger the
conductor needs to be.
The below short list of metric sizes is specifically for your
use with BMW motorcycles, as the metric numbers are what BMW uses on its
diagrams.
NOTE!....these are not metric gauge sizes, but metric wire sizes, in mm.
0.5 metric is 20+ ga, use 20 ga
0.75 metric is 19 ga, use 18 ga
1.0 metric is 17 ga, use 16 ga
1.5 metric is 15 ga, use 14 ga
2.5 metric is 13 ga, use 12 ga
4 metric is 11 ga, use 10 ga
16 metric is 5 ga, use 4 ga
Diagrams on airhead schematics, colors:
BL blue...usually, not always, oil pressure, ALT (GEN) lamp;
alternator
BR brown...always the ground, battery negative, frame ground.
GE yellow...low beam
GR grey(gray)...rear lights
GN green... usually, not always, ignition coil connection
RT red...battery, and often from the light switch and ignition
switch
SW black...usually, not always, the starter, and some functions to
the ignition coil and starter
VI violet
WS white...high beam
TR transparent (not airheads)
If two colors are used on a wire, it is USUALLY shown with a hyphen,
example: RT-GE
Two color wires MAY have some related function to the stripe color, or
the body color, or both, or neither.
BOSCH codes:
**Note: These numbers/letters are found on all sorts of devices in
your airhead, from sockets to coils. This is a comprehensive list,
and it combines Bosch published codes AND the specifications in
DIN72552, thus some listings will have 1 or more possible
functions/devices. This list covers FAR more than that used on
airheads. Note that sometimes there is a bit of ambiguity in actual
use.
1 Ignition, coil, primary, breaker, low voltage, distributor
1a If a dual breaker, #1
1b If a dual breaker, #2
2 Ignition, switched ground, magneto
4 Ignition coil, ignition distributor, high voltage
If two circuits, then 4a is coil 1 terminal 4,
and 4 b is coil 2 terminal 4
15 +, primary, ignition coil, ignition switch output
15a output of ignition dropping resistor
17 glow plug of starter switch, start
19 preheat
30 from battery, + direct
30a series parallel switch, 12/24 volts, input, direct, from battery
31 battery negative (-), return line or ground, could be via switch
or relay
32 to 33R all are for series-parallel arrangements of battery 12/24
volt switching, MANY functions.
32 return line, polarity reversed at 32, 33, possible
33 main return
33a self parking switch off
33b shunt field
33f second lower speed
33g third lower speed
33h fourth lower speed
33L CCW rotation
33R CW rotation
45 starter, separate relay, output, main current input
45a 2 starter parallel operation, output 1 and input 1 and 2
45b as above, output 2
48 starter and start repeat relay for monitoring starter
49 turn signal flasher, input
49a turn signal flasher, output
49b turn signal flasher, output, circuit 2
49c turn signal flasher, output, circuit 3
50 starter direct control
50a series-parallel, output of battery switch
50b series-parallel, 2 starters, sequential control
50c input, starter relay 1
50d input, starter relay 2
50e input, starter lock relay
50f output, starter lock relay
51 + to light switch, alternator DC at rectifier.
51e alternator, as above, but with choke coil for day driving
52 trailer signals
53 wiper motor (can have -a,b,c,e,i functions)
54 brake stop light-directional light, trailer items
55 fog lights
56 lights, tach lights, headlights
56a high beam and high beam indicator
56b low beam (d is used for flasher contact)
57 parking light, side markers, -a is parking, L is left, R is right
58 lights...accessory, sidecar, rear. Also used for instruments,
license plate lights,
some side markers, and variable
intensity functions
59 alternator a.c....and other functions specialized internally
61 indicator charge light
71 horns
72 alarm, emergency lights
75 radio, cigarette lighter
76 loudspeaker
77 door control
81-84 various styles of switches
85-86 switching relay
87-88 more relays
((see link at bottom of page regarding relay contact numbering))
D- dynamo
D+ + generator output, dynamo +
Df field of generator, dynamo field, Df1 is #1, Df2 is #2
F as above
B+ Battery +, + on regulator
B- Battery negative (-)
Directional signals:
C first indicator lamp
Co maintain
C2 second lamp
C3 third lamp
L turn signal, left
R turn signal, right
For a very nice article, animated, on relays and
their functions, with many specifics for airheads,
go to www.airheads.org and
click on left side for Technical Tips, and find Joe Cuda's
article.
For more details on the pin numbers of parts,
particularly relays, sketches, diagrams....etc, see:
http://www.e38.org/understanding euro wiring diagrams.pdf
Below is a much more detailed chart on wire details. Note that
the 'Maximum amps for power transmission' is very conservative, and can almost
always be exceeded by a considerable amount in practical use, in particular for
short lengths of wire. Rated capacities for wire are, in any case,
rules-of-thumb, although there are standards for such as house wiring.
Values in the below table for maximum amperes need to be used in conjunction
with just how you intend to use the wires; bundled? solid wires? stranded wires?
open air? temperatures? and many other factors.
But, for motorcycle use, the below table is quite conservative.
NOTE!!....in the AWG gauge column are listed some metric sizes, which are actual metric GAUGE sizes. These are NOT the sizes for wires as used by BMW in its wiring diagrams. Those BMW diagram sizes are conductor diameters in mm...so see that third column, below.
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revisions:
09/19/2009: add hyperlink for the euro
wiring sketches and diagrams; add note regarding airheads.org
article on Joe 'Cuda's article
01/14/2012: add commentary, and add chart and commentary for metric versus
American, etc.
©
copyright 2012, R. Fleischer