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BMW Motorcycles, cars, and most all European Vehicles:
Metric & American Wires, Colors, Bosch Codes, sources
and, some information about schematic diagrams.

© copyright 2014, R. Fleischer
wires&codes.htm-26


This first section is a discussion of wiring diagrams themselves, and following this section is the technical information about connections, colors, etc.

Most of the various published articles/charts for the various functions of wire terminal numbers, colors, etc., are overly complicated; or, show connections somewhat similar to architectural diagrams, and can be VERY confusing to those trying to work on their vehicles. There is often misleading information on functions that are especially confusing if you do not understand their methodology/terminology. Where American (SAE) sizes are shown, the information is also often misleading or confusing.

BMW is very consistent in the publishing of its schematic diagrams. BMW diagrams are quite clear and detailed, easy to follow. NOT SO are such as Clymers and Haynes and some car repair manuals. Clymers tends to publish confusing black and white sketches that have errors; and are hard to read from one page to another in many instances. Haynes tends to publish their own method of color coding that often is confusing, leading you astray, sometimes with the same page to page problems as Clymers.

BMW's own diagrams are available on factory service CD's, and also FREE on a number of websites including my own that you are reading this on.  BMW published Airhead diagrams (for service work by dealerships) in a much easier format, similar to what was in early owner's booklets, but much larger and easier to read, that had all the pertinent details (and expanded in some instances) and had none of the complications mentioned above from Haynes, Clymers, etc.  It is THOSE BMW TYPES that I generally put on this website for you. The diagrams I have are almost entirely of the BMW types, because THAT is what YOU should be using; is in many owners booklets; and in BMW technical literature. The diagrams are very easy to use, give wire sizes, colors, and terminal numbers, and often show the switching functions inside an assembly.
Because of these concerns, etc., I seldom publish any other form of schematic.

K1, K75, K100, K1100 bike owners:
BMW quit, many years ago, publishing their electrical diagrams in owners booklets. They still did SOME of it in the factory service manuals, but in most instances they had SEPARATE 'books' for the electrical's. Thus, unless you could find these on-line, you had to spend a fair amount of money to get all of the electrical's coverage for your bike.   I do not recommend anyone (but a tech nerd like myself or a shop)
own them. These separate large books are THE VERY BEST diagrams, with large fold-out pages and cover several languages and there is a lot of detail early-on in the books too. These books are NOT as
useful for most all of you (they are NOT available for Airheads) due to ONE thing (besides the
typical price for ONE booklet, that may or may not cover ALL of YOUR bike!!). What makes them less
useful to most of you is that the booklets show wiring by SYSTEMS or GROUPS. That is, one diagram
may be for ENGINE functions, one for FRAME functions, one for Accessories, and so on. Each of
those diagrams will have pertinent details JUST for THOSE systems. Thus, ALL connections to the
SAME place (battery? Ignition switch? etc.) are NOT SHOWN on ANY ONE diagram (and, I include the groups mentioned above, AND, accessories). This type of publishing method is necessary for the rather complicated computer controlled K bike's, but not for Airheads. As mentioned, they were never made this
way for Airheads.

The SEPARATE diagrams that ARE available for Airheads are those for such as Accessories like heated grips, emergency lights, swing out lamps for the RT, etc. I think I have ALL OF THEM for you on this website.
 



Wiring diagrams, sometimes called Electrical Schematic Diagrams, the German's call them Stromlaufpläne, will usually show the wire insulation color and the cross-sectional size (in mm) of the conductor. To explain that a bit more, in the metric system, wire size is specified by the effective AREA in terms of square millimeters.   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 metric wiring, you'd use the same or next larger mm size.
Gauge sizes can be confusing.  In the American System (SAE), the gauge number gets SMALLER as the wire size INcreases.  Sheet metal gauge & wire gauge sizes are the SAME for America.  

Nerdy information:  The American wire gauge system has wire getting thinner as the number goes UP because in the early days (and much, still, today), in order to thin the larger wire that thinner wire comes from, multiple passes through progressively smaller dies were needed.  A 30 ga wire supposedly had 30 passes.

The Germans have adopted the standardized metric system, and it is vastly easier to use and understand.

Another confusing issue can come about because the measured wire diameter (and conversion to the metric cross-sectional size, if you wanted to do that) and thusly the current capacity....with STRANDED wire.... is not the same depending on the number of strands in any one measured size of stranded wire.   This comes about from spacing, and from the irregularities in a bundling of wires.

It is GOOD FORM to install only factory type of wiring, never EVER mixing American color methods with DIN type.  By this, as example:  If you are patching into a existing wire or adding a wire, etc., on a German vehicle, do NOT use anything but the original wire color codes as appropriate!
This does NOT mean you cannot use American sizes of wire.

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.  Use stock or larger sizes, depending on your purpose.
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

The above values are approximate, and err on the side of reliability and are ACCEPTED equivalents, and will be OK for bundled wires, which require more safety in wire thickness.
A chart of American gauge sizes and with metric diameters, with resistance, current capacity, etc., is at the end of this article.

Diagrams on schematics, colors:

Many wires have a secondary color called a stripe, thus, you could have a gray wire with a black stripe.  To my present knowledge, only one additional stripe color is ever used on vehicles.

A gray wire with a black stripe will be shown with the main body color first:  GRSW or GR/SW or GR-SW.   Do not confuse WS and SW.  Do not think that GR (GRAY) means green.
Some descriptions will have the first letter capitalized and the second letter in lower case. 
Sw means the same thing as SW and vice versa.


Two color wires MAY, and usually do, have the main wire color correspond to the normal broad function, and the stripe has a sub-function.  Thus, a brown wire with a yellow stripe has some sort of function related to brown in a grounding or common wiring function.




Transparent, TR or Tr, is almost never used, and
not listed above.
 

The following colors are for the main body color of the wire.
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 ...seldom used


Here is a link to an article on the airheads.org website that explains colors and functions
differently:
http://www.airheads.org/technical-tips-articlesmenu-98/302-wiring-color-codes



BOSCH device connection codes:

**Note: These numbers/letters are found on all sorts of devices in your motorcycle, 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 most BMW vehicles. Note that sometimes there is a bit of ambiguity in actual use.  The actual total list of all possible connection codes is MUCH longer than on this page.  Letters are added to the single or twin numbers to identify particulars.

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    charge light indicator
71    horns
72    alarm, emergency lights
75    radio, cigarette lighter
76    loudspeaker
77    door control


81-88   various styles of switches and relays contacts/connections.
The contacts and coils are identified by letters, typically a, b, c.
Generally, series 81, 82, 83 are normally closed relays; series 87 is normally closed; series 88 is normally open.  Terminal 86 a, b and c are assigned to relay coils.  Terminals 87, 88 are typically assigned to contact inputs, with letters added for contact outputs, unless 30 is the input, then these are outputs.


D-    Alternator/generator negative
D+    Alternator/generator + output
Df     Alternator rotor/field.    
U, V, and W:  Alternator 3 phase connections

B+   Battery +; + on regulator
B-    Battery negative (-)

Directional signals: 
C      First indicator lamp
C2    Second indicator lamp
C3    third lamp
L      turn signal, left side
R      turn signal, right side

 

For more details on the pin numbers of parts, particularly relays, sketches, diagrams....etc, see:
http://www.e38.org/understanding euro wiring diagrams.pdf
 


SOURCES for colored/coded wires (new wire; you can always get used wires from wrecked cars...but new is much nicer!):
1.  http://eagleday.stores.yahoo.net/neauwi.html    Metric sizes
2.  http://riwire.com     American gauges sizes


Two charts, confusing?  maybe...but see BOTH:

Below is a much more detailed chart on wire details. MUCH of this first chart (of two charts) is nerdy information, unlikely to be of much use to you.   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 #1 is quite conservative.

CONFUSING NOTE!!....in the AWG gauge column are ALSO 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, they are listed here to cause confusion (well, not, but they do/can).   In BMW vehicle diagrams, the wire sizes are conductor diameters in effective mm squared; the chart below has the value in its diameter...see that third column, below.  NOTE that this is a chart of absolutes, regarding SIZES.  In practice, one should use a larger gauge in most instances....see the equivalents noted very early in this article, for those practical gauge equivalents to mm sizes.  While you are unlikely to see this, note how the very small metric sizes are named, near the bottom of the chart, in the AWG vertical column!   This very small wire is used in such as winding transformers, etc....and is where Metric sizes get confusing!  Nerdy information!

Table #1

AWG gauge Conductor
Diameter Inches
Conductor
Diameter mm
Ohms per 1000 ft. Ohms per km Maximum amps for chassis wiring Maximum amps for
power transmission
Maximum frequency for
100% skin depth for solid conductor copper
OOOO 0.46 11.684 0.049 0.16072 380 302 125 Hz
OOO 0.4096 10.40384 0.0618 0.202704 328 239 160 Hz
OO 0.3648 9.26592 0.0779 0.255512 283 190 200 Hz
0 0.3249 8.25246 0.0983 0.322424 245 150 250 Hz
1 0.2893 7.34822 0.1239 0.406392 211 119 325 Hz
2 0.2576 6.54304 0.1563 0.512664 181 94 410 Hz
3 0.2294 5.82676 0.197 0.64616 158 75 500 Hz
4 0.2043 5.18922 0.2485 0.81508 135 60 650 Hz
5 0.1819 4.62026 0.3133 1.027624 118 47 810 Hz
6 0.162 4.1148 0.3951 1.295928 101 37 1100 Hz
7 0.1443 3.66522 0.4982 1.634096 89 30 1300 Hz
8 0.1285 3.2639 0.6282 2.060496 73 24 1650 Hz
9 0.1144 2.90576 0.7921 2.598088 64 19 2050 Hz
10 0.1019 2.58826 0.9989 3.276392 55 15 2600 Hz
11 0.0907 2.30378 1.26 4.1328 47 12 3200 Hz
12 0.0808 2.05232 1.588 5.20864 41 9.3 4150 Hz
13 0.072 1.8288 2.003 6.56984 35 7.4 5300 Hz
14 0.0641 1.62814 2.525 8.282 32 5.9 6700 Hz
15 0.0571 1.45034 3.184 10.44352 28 4.7 8250 Hz
16 0.0508 1.29032 4.016 13.17248 22 3.7 11 k Hz
17 0.0453 1.15062 5.064 16.60992 19 2.9 13 k Hz
18 0.0403 1.02362 6.385 20.9428 16 2.3 17 kHz
19 0.0359 0.91186 8.051 26.40728 14 1.8 21 kHz
20 0.032 0.8128 10.15 33.292 11 1.5 27 kHz
21 0.0285 0.7239 12.8 41.984 9 1.2 33 kHz
22 0.0254 0.64516 16.14 52.9392 7 0.92 42 kHz
23 0.0226 0.57404 20.36 66.7808 4.7 0.729 53 kHz
24 0.0201 0.51054 25.67 84.1976 3.5 0.577 68 kHz
25 0.0179 0.45466 32.37 106.1736 2.7 0.457 85 kHz
26 0.0159 0.40386 40.81 133.8568 2.2 0.361 107 kH
27 0.0142 0.36068 51.47 168.8216 1.7 0.288 130 kHz
28 0.0126 0.32004 64.9 212.872 1.4 0.226 170 kHz
29 0.0113 0.28702 81.83 268.4024 1.2 0.182 210 kHz
30 0.01 0.254 103.2 338.496 0.86 0.142 270 kHz
31 0.0089 0.22606 130.1 426.728 0.7 0.113 340 kHz
32 0.008 0.2032 164.1 538.248 0.53 0.091 430 kHz
Metric 2.0 0.00787 0.200 169.39 555.61 0.51 0.088 440 kHz
33 0.0071 0.18034 206.9 678.632 0.43 0.072 540 kHz
Metric 1.8 0.00709 0.180 207.5 680.55 0.43 0.072 540 kHz
34 0.0063 0.16002 260.9 855.752 0.33 0.056 690 kHz
Metric 1.6 0.0063 0.16002 260.9 855.752 0.33 0.056 690 kHz
35 0.0056 0.14224 329 1079.12 0.27 0.044 870 kHz
Metric 1.4 .00551 .140 339 1114 0.26 0.043 900 kHz
36 0.005 0.127 414.8 1360 0.21 0.035 1100 kHz
Metric 1.25 .00492 0.125 428.2 1404 0.20 0.034 1150 kHz
37 0.0045 0.1143 523.1 1715 0.17 0.0289 1350 kHz
Metric 1.12 .00441 0.112 533.8 1750 0.163 0.0277 1400 kHz
38 0.004 0.1016 659.6 2163 0.13 0.0228 1750 kHz
Metric 1 .00394 0.1000 670.2 2198 0.126 0.0225 1750 kHz
39 0.0035 0.0889 831.8 2728 0.11 0.0175 2250 kHz
40 0.0031 0.07874 1049 3440 0.09 0.0137 2900 kHz
               

 

Table #2

Hopefully this table will explain a few things better.  NOTE that this table includes the cross-section (mm²) information; and that AWG sizes as large as 6/0 are included. 
 

The below table gives closest equivalent size cross references between metric and American wire sizes. In Europe, wire sizes are expressed in cross sectional area in mm² and also as the number of strands of wires of a diameter expressed in mm. For example 7/0.2 means 7 strands of wire each 0.2mm diameter. This example has a cross sectional area of 0.22mm². In America, the commonest system is the AWG numbering scheme, where the numbers are applied not only to individual strands but also to equivalent size bunches of smaller strands. For example 24AWG could be made of 1 strands of 24AWG wire (1/24) or 7 strands of 32 AWG wire (7/32).

AWG Number

Ø [Inch]

Ø [mm]

Ø [mm²]

6/0 = 000000

0.580

14.73

170.30

5/0 = 00000

0.517

13.12

135.10

4/0 = 0000

0.460

11.7

107

3/0 = 000

0.410

10.4

85.0

2/0 = 00

0.365

9.26

67.4

1/0 = 0

0.325

8.25

53.5

1

0.289

7.35

42.4

2

0.258

6.54

33.6

3

0.229

5.83

26.7

4

0.204

5.19

21.1

5

0.182

4.62

16.8

6

0.162

4.11

13.3

7

0.144

3.66

10.5

8

0.128

3.26

8.36

9

0.114

2.91

6.63

10

0.102

2.59

5.26

11

0.0907

2.30

4.17

12

0.0808

2.05

3.31

13

0.0720

1.83

2.62

14

0.0641

1.63

2.08

15

0.0571

1.45

1.65

16

0.0508

1.29

1.31

17

0.0453

1.15

1.04

18

0.0403

1.02

0.823

19

0.0359

0.912

0.653

20

0.0320

0.812

0.518

21

0.0285

0.723

0.410

22

0.0253

0.644

0.326

23

0.0226

0.573

0.258

24

0.0201

0.511

0.205

25

0.0179

0.455

0.162

26

0.0159

0.405

0.129

27

0.0142

0.361

0.102

28

0.0126

0.321

0.0810

29

0.0113

0.286

0.0642

30

0.0100

0.255

0.0509

31

0.00893

0.227

0.0404

32

0.00795

0.202

0.0320

33

0.00708

0.180

0.0254

34

0.00631

0.160

0.0201

35

0.00562

0.143

0.0160

36

0.00500

0.127

0.0127

37

0.00445

0.113

0.0100

38

0.00397

0.101

0.00797

39

0.00353

0.0897

0.00632

40

0.00314

0.0799

0.00501

 



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.
08/11/2012:  Clear up possible misunderstandings about how the colors are used when there is a stripe.
                    I have been informed that Joe 'cuda's article was removed from the .org website. 
                    added note
10/15/2012:  Add QR code, add language button, update Google Ad-Sense code
11/05/2012:  edit and add more material and remove information on Joe Cuda's article, which is no longer
                    on the Airheads.org website (unfortunately, it was very very good).
11/06/2012:  Add discussion section at beginning of article.
04/23/2012:  Change wording, slightly, about "German Metric System"; minor other changes.
06/14/2013:  Add Sources.
06/29/2013:  Try to clarify the differences between American and Metric wire codes and sizes, and add
                     table #2.
08/28/2014:  Add link to Joe's article on Airheads.org

© copyright 2014, R. Fleischer
 

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