WIRING TERMINAL DESIGNATIONS
AND COLOR

      Did you know that Volkswagen and almost every other European car, Porsche, Audi, Saab, Volvo, BMW, Mercedes etc, has standard numbers and color coding for all of it's electrical wiring. Suppose you wanted to install an accessory, like a radio, but you only wanted the radio to have power when the ignition was on so you don't run the battery down by accident. Any black wire on the car is connected to terminal number 15 which is only "hot" or positive when the key is in the on or the start position so any accessory attached to a black wire, that is a large enough gauge (size), could be spliced into and used for this purpose. 
       This is only an example and maybe a bad one because later model cars  use a "load reduction relay" which is preferable and you could do serious damage to a 1996 and up VW with OBDII. If you don't know what a "KAN bus" connection is then you shouldn't attempt to install a non-VW aftermarket radio. Still you get the point I hope.  
    Lets say for example any;
     Wire that is solid brown in color, goes to a terminal 31 and is a direct negative connection to chassis ground. That should be easy to memorize. Brown, the color of earth, is ground. 
     All solid red wires go to terminal connections with the number 30 marked on them, are hot or positive all the time and are not fused. That is to say there are no switches between them and the positive side of the battery.
      If you see a wire that has 2 or more colors and 1 color is brown then that wire probably grounds indirectly thru a relay or some other device instead of directly to the chassis or the battery.
      If you see a wire with red and another color then it is most likely hot (positive) and fused and possibly provides power from a device like a relay and not directly from the battery.
      A black wire with a second color receives its power indirectly also but will only be hot when the ignition switch is in the on or start position as is the case with all black wires.
      
     With this info you can tell a lot more about the wires you are looking at without having to constantly refer to the schematics in a book or a CD ROM.

WIRING TERMINAL ID by NUMBER
Those that are color highlighted are more important

Terminal #           Definition
1 . . . . . . . . . . . .Ignition Coil, Distributor Low-Tension Circuit GREEN WIRE TO DISTRIBUTOR (Early model with ignition points)
Ignition Distributor With Two Insulated Circuits
1a . . . . . . . . . .to Ignition Point Set I
1b . . . . . . . . . .to Ignition Point Set II
Ignition Coil, Distributor
4 . . . . . . . . . . . High-Tension Circuit
Ignition Distributor With Two Insulated Circuits
4a . . . . . . . . . .Terminal 4, from Coil I
4b . . . . . . . . . .Terminal 4, from Coil II
15 . . . . . . . . . .Switch-Controlled Positive Downstream from Battery (from Ignition Switch)    BLACK WIRE
15a . . . . . . . . .In-Line Resistor Terminal Leading to Coil & Starter
Glow-Plug Switch
17 . . . . . . . . . .Start
19 . . . . . . . . . .Preglow
30 . . . . . . . . . .Line from Battery Positive Terminal (Direct) RED WIRE
31 . . . . . . . . . .Return Line from Battery Negative Terminal  BROWN WIRE
or Ground (Direct)
31b . . . . . . . . .Return Line to Battery Negative Terminal or Ground Via
Switch or Relay (Switch-Controlled Ground)
Electric Motors
32 . . . . . . . . . .Return Line*
33 . . . . . . . . . .Main Connection*
33a . . . . . . . . .Self-Parking Switch-Off
33b . . . . . . . . .Shunt Field
33f . . . . . . . . .for Reduced-RPM Operation, Speed 2
33g . . . . . . . . .for Reduced-RPM Operation, Speed 3
33h . . . . . . . . .for Reduced-RPM Operation, Speed 4
33L . . . . . . . . .Rotation to Left (Counterclockwise)
33R . . . . . . . . .Rotation to Right (Clockwise)
*Polarity Reversal of 32/32 Possible
Starter
45 . . . . . . . . . .Separate Starter Relay, Output: Starter;
Input: Primary Current
Flasher Relay (Pulse Generator)
51 . . . . . . . . . .Input
49a . . . . . . . . .Output
49b . . . . . . . . .Output to Second Flasher Relay
49c . . . . . . . . .Output to Third Flasher Relay
Battery Switching Relay
50a . . . . . . . . .Output for Starter Control
Start-Locking Relay
50e . . . . . . . . .Input
50f . . . . . . . . .Output
Start-Repeating Relay
50g . . . . . . . . .Input
50h . . . . . . . . .Output
AC Generator (Alternator)
51 . . . . . . . . . .DC Voltage at Rectifier
51e . . . . . . . . .DC Voltage at Rectifier with Choke Coil for Daylight Operation

Terminal    Definition
Starter
52 . . . . . . . . . .Starter Control (Direct)
53 . . . . . . . . . .Wiper Motor, Input (+)
53a . . . . . . . . .Wiper (+), End Position
53b . . . . . . . . .Wiper (Shunt Winding)
53c . . . . . . . . .Electric Windshield Washer Pump
53e . . . . . . . . .Wiper (Brake Winding)
53i . . . . . . . . .Wiper Motor with Permanent Magnet & Third Brush
(for Higher Speed)
55 . . . . . . . . . .Front Fog Lamp
56 . . . . . . . . . .Headlights
56a . . . . . . . . .High Beam with Indicator Lamp    WHITE WIRE
56b . . . . . . . . .Low Beam    YELLOW WIRE
56d . . . . . . . . .Headlight Flasher Contact
57 . . . . . . . . . .Parking Lamps (in some export markets)
57a . . . . . . . . .Parking Lamps
57L . . . . . . . . .Parking Lamps, Left
57R . . . . . . . . .Parking Lamps, Right
58 . . . . . . . . . .Side-Marker Lamps, Taillamps, License Plate
& Instrument Illumination
58d . . . . . . . . .Rheostatic Instrument Illumination, Tail- & Side-Marker Lamps
58L . . . . . . . . .Left
58R . . . . . . . . .Right, License Plate Lamps
AC Generator (Alternator)
(Magneto Generator)
59 . . . . . . . . . .AC Voltage Output, Rectifier Input
59a . . . . . . . . .Charging-Armature Output
59b . . . . . . . . .Taillamp Armature, Output
59c . . . . . . . . .Stop-Lamp Armature, Output
61 . . . . . . . . . .Charge Indicator Lamp
Tone-Sequence Controller
71 . . . . . . . . . .Input
71a . . . . . . . . .Output to Horns I & II (Bass)
71b . . . . . . . . .Output to Horns 1 & 2 (Treble)
75 . . . . . . . . . .Radio, Cigarette Lighter
76 . . . . . . . . . .Speakers
77 . . . . . . . . . .Door Valve Control
Switches, Normally Closed (NC) Contacts & Changeover Contacts
81 . . . . . . . . . .Input
81a . . . . . . . . .First Output on NC-Contact Side (No Contacts)
81b . . . . . . . . .Second Output on NC-Contact Side
82 . . . . . . . . . .Input
82a . . . . . . . . .First Output
82b . . . . . . . . .Second Output
82z . . . . . . . . .First Input
82y . . . . . . . . .Second Input


Terminal    Definition
Multiple-Position Switch
83 . . . . . . . . . .Input
83a . . . . . . . . .Output (Pos. 1)
83b . . . . . . . . .Output (Pos. 2)
83L . . . . . . . . .Output (Left)
83R . . . . . . . . .Output (Right)
Current Relay
84 . . . . . . . . . .Input: Actuator & Relay Contacts
84a . . . . . . . . .Output: Actuators
84b . . . . . . . . .Output: Relay Contacts
Switching Relay
85 . . . . . . . . . .Output: Actuator (Negative Winding End or Ground)
Input: Actuator
86 . . . . . . . . . .Start of Winding
86a . . . . . . . . .Start of Winding or First Winding Coil
86b . . . . . . . . .Winding Tap or Second Winding Coil
Normally Closed (NC) Relay Contact & Changeover Contacts
87 . . . . . . . . . .Input
87a . . . . . . . . .First Output (NC-Contact Side)
87b . . . . . . . . .Second Output
87c . . . . . . . . .Third Output
87z . . . . . . . . .First Input
87y . . . . . . . . .Second Input
87x . . . . . . . . .Third Input
Normally Open (NO) Relay Contact
88 . . . . . . . . . .Input
88z . . . . . . . . .First Input
88y . . . . . . . . .Second Input
88x . . . . . . . . .Third Input
Normally Open (NO) Relay Contact & Changeover Contacts (NO Side)
88a . . . . . . . . .First Output
88b . . . . . . . . .Second Output
88c . . . . . . . . .Third Output
Generator/Alternator & Voltage Regulator
B+. . . . . . . . . .Battery Positive Terminal
B- . . . . . . . . . .Battery Negative Terminal
D+. .  . . . . . . . . Generator Positive Terminal
C . . . . . . . . . . Generator Negative Terminal
DF . . . . . . . . . Generator Field Winding
DF1 . . . . . . . . Generator Field Winding 1
DF2 . . . . . . . . Generator Field Winding 2
Alternator
U, V, W . . . . . .Three-Phase Terminals
Turn Signals (Turn-Signal Flasher)
C . . . . . . . . . . .Indicator Lamp 1
C0 . . . . . . . . . .Main Terminal Connection for Indicator Lamp Not
Connected to Turn-Signal Flasher
C2 . . . . . . . . . .Indicator Lamp 2
L . . . . . . . . . . .Left-Side Turn Signals
R . . . . . . . . . . .Right-Side Turn Signals