Letter designation | Structural element |
A | battery |
IN | starter |
WITH | three-phase current generator |
D | ignition and starter switch |
E | manual override switch |
F | mechanical switch |
G | sensor, control device |
H | sound signal (simple beep, two tone beep, etc.) |
J | relay, control device |
K, L, M, W, X | signal lamps, lamps, lamps |
N | electrical valves, resistors, switching devices |
ABOUT | distributor |
P, Q | spark plug tip, spark plug |
R | radio |
S | fuse |
T | detachable connections |
V | electric motors |
Most consumers are connected by two wires. However, it is often possible to trace the passage of only one wire from the consumer to the battery or generator. The second wire is screwed to the body, engine or gearbox after a few centimeters, or connected to the contact tongue.
Metal parts: ground contact
Metal parts, which are called mass in electrical engineering, are capable of conducting current, which saves on wires. Instead of running a wire to the negative pole of the battery, the case is used as this wire. If a consumer does not work, then often this is due to the fact that he is not connected to the mass. Sometimes a simple connection to the body is not enough, in this case an additional wire is laid, which, as a rule, has a brown color.
Colors and numbers
The Audi A4 has a large number of wires, but the mess of wires seems to be so only at first glance: the wires are color-coded, most of the connections to the connectors and relays are numbered. Numbering is carried out according to DIN standards. On white wires, additional numbers are used for identification. The designation of the terminals is also standardized. Some important terminals:
- Terminal 30. Battery voltage is always applied to this terminal. The wires are usually red or red with colored stripes.
- Terminal 31. Connects to ground, usually with a brown wire.
- Terminal 15. Power is supplied to this terminal through the ignition switch. Current through the wires connected to this terminal only flows when the ignition is on. The wires are usually green or green with colored stripes.
- Terminal X. Increasingly powerful consumers, such as high beam lamps, are fed through this terminal. Current flows through the terminal when the ignition is on, but when the starter is operated, the current is interrupted. This allows full battery voltage to be applied to the ignition system.
Basic colors and purpose of wires
Red wires. Pos flowing current from the positive pole of the battery or generator (with the engine running). If the negative cable is not disconnected from the battery, a short circuit or sparks may occur if the tools are not handled carefully.
Black wires. Current to black wires; is supplied through the ignition lock when the ignition is on-| nii, and with the exception of the ignition system and fuel injection, power is supplied only to those consumers who should be fed only when the vehicle is in operation.
Brown wires. These wires are used for direct connection to ground. In order for the circuit to be closed, current consumers must be connected to the housing by means of black (not brown) wires.
Gray wires. They are used for power supply circuits of position, rear and parking lights, as well as for powering a license plate light.
In addition, the following colors are used to designate wires: blue, yellow, green, purple, orange and white.
The numbers that can be seen on circuit diagrams next to the wire color designation indicate the cross section of the wire. If the wire connects to the plug connection (T), then combinations of numbers indicate the type of connection and the point of contact:
- T32/27 = 32-pin plug connection with contact point 27.
Some wires have additional colored stripes for more detailed identification.
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