| WIRING STANDARDS
By Matt De Maria
Have you ever wanted to quickly diagnose an electrical problem in your Porsche without going to the wiring diagram?
RED is for wires coming directly but unswitched from the battery.
BLACK is for wires coming from the ignition switch, and is used to describe wires that are able to deliver power that is controlled
BROWN is used for wires that go to the ground on the car.
WHITE wires are used to go to the high beams of the headlights. Sometimes you will find a colored runner on one of the white
YELLOW wires are used for the low beam circuit; a runner is sometimes also used here to differentiate between right and left.
GREY wires are used for the park light circuits (tail light,tag light, etc.)
BLACK runners are sometimes used for the left lights and RED runners for the right side.
BLUE is used for wires going to the indicator lights on the dashboard.
BLACK wires with colored runners are sometimes used for the turn signal functions.
WHITE runners are used for the left side and GREEN for the right side.
There is also a standardized code for the pin numbers on the electrical components (This is still used):
The number 30 or 30/51 next to a terminal indicates that battery voltage goes to this terminal.
The number 15/54 or 15 indicates that `keyed' battery power goes to this terminal.
The number 31 means that this point has to go to ground.
The number 50 indicates the power line from the ignition switch to the starter solenoid trigger terminal.
The numbers 53, 53a, and 53b are used for the windshield wiper motor.
The number 54 is used for the turn signal circuit.
The number 56 is used for the output of the headlight switch into the flasher switch.
The number 56a is used for the high beams, and 56b is used for the low beams.
The number 55 is used for the fog lights.
The number 86 is the power to the relay winding.
The number 87 is the normally open (static mode or unenergized mode) output of the relay.
The number 87a is the normally open contact for two switch relays.
A normally open relay is shown in Drawing #1, and a normally closed relay is shown in Drawing #2.
Now using the two codes together, we can verify the wires to an electrical item by the color and also verify the function of the electrical
If we look at a 356A light switch, we have numbered terminals 30, 58, and 56. For wires, we have two red, two gray, and
From our standard code we also know that the two #30 terminals and red wires are hot (activates a test light) because red wires
Again looking at a horn relay on the 356A we find in Drawing #4 the same codes prevail.
Reviewing our standard codes we know #30/51 and #86 are both hot terminals. Terminal #85 is the ground side of the coil in the
In the 1974 911 wiring diagram, we will look at the headlight relay in the current tracks #4 and #5. See Drawing #5.
From our codes we know terminal #87a (the normally closed set of points) goes to the high beam circuit, and terminal #87 goes
In the wiring diagrams for the `85 Carrera we will look at B35 on the fourth wiring sheet. See Drawing #6.
This relay's function can be understood with the help of the number codes and the color codes. This is a cascading relay or a
In summary, knowing the color and number codes will greatly facilitate understanding the electrical system design, and thus lead to