How much do you know about car wiring harnesses?

The wiring harness must first be composed of various automotive wires, such as GPT,TXL AVSS,AVS,FLRY-B, FLRY-A.


Automobile wiring harnesses can be divided into engine wiring harnesses, instrument wiring harnesses, lighting wiring harnesses, air conditioning wiring harnesses and auxiliary electrical wiring harnesses according to the composition of the system.

According to the layout position (generally the dashboard is the core position), it can be divided into:

Front wiring harness: instrument, engine, headlight assembly, air conditioner, battery, etc.

Rear wiring harness: tail light assembly, license plate light, trunk light, etc.

Roof harness: door, dome light, audio horn, etc.


Basic components of automotive wiring harness

There are two types of common car wiring harness wire colors, which are single-color wires and double-color wires.

Under normal circumstances, the color code of a single-color wire is represented by its first letter in English.

The color code of the two-color wire is expressed in the order of the main and auxiliary colors (the main color is also called the background color, and the auxiliary color is also called the stripe color or the logo color) in the form of the combination of its English initials. The main color ribbon is wider and the auxiliary color ribbon is narrower .

Wire diameter:

Usually the wire diameter we refer to is the diameter of the guide wire in millimeters (mm).

And most of the time we will measure the thickness of the wire by the cross-sectional area of the wire (unit: square millimeter)

It should be noted that: wire diameter = cross-sectional area of a single core wire x number of wires

Common cross-sectional areas are 0.5mm2, 0.75mm2, 1.0mm2, 1.5mm2, 2.0mm2, 2.5mm2, 4.0mm2, 6.0mm2. Wires with different thicknesses have their own allowable current values, which are used for the connection between electrical devices of different powers. Common sizes like AVS 0.5mm automotive wire, FLRY-A 0.75mm, FLRY-B 1.0MM for automotive and so on.

The usual wire diameter selection scheme is:

0.5mm2 is mostly used in instrument lights, indicator lights, door light wiring harnesses

0.75mm2 is mostly used in license plate light, tail light assembly, trunk light wiring harness

1.0mm2 is mostly used in turn signal and fog lamp wiring harness

1.5mm2 is mostly used in headlights and horn wiring harnesses

2.5mm2~4.0mm2 are mostly used in motor armature, ground wire harness

For the battery grounding wire and the positive power supply wire, because the load current value it bears is very large, the thicker wire is generally larger than ten square millimeters.


In order to ensure that each wire harness in the automobile circuit will not be accidentally overloaded, wires of different wire diameters have corresponding fuses. When the load capacity of the wire is exceeded, the fuse will blow and disconnect the circuit, thus realizing the function of protecting the circuit.

Therefore, the selection of the ampere value of the fuse must not be casual. If the selected value is too large, it will not play a protective role; if it is too small, the normal operation of the electrical equipment on the line cannot be guaranteed.

In automotive circuit communication, it is always interfered by interference signals such as electromagnetic waves, resulting in signal distortion and errors. In order to reduce interference as much as possible, on the basis of ordinary wires, twisted pairs and shielded wires are introduced to block interference signals.


Among them, twisted pair is the simplest method, that is, a wire bundle formed by two mutually insulated wires twisted together according to a certain specification.

The signals generated on it are equal in size and opposite in direction, and can cancel each other, thereby reducing the interference of their own signals to the outside world, and at the same time preventing external electromagnetic interference.


The anti-interference ability of the shielded wire is better than that of the twisted pair. It adds a metal shielding layer between the twisted pair and the outer insulating layer. Common shielded wires include aluminum foil shielded wires and braided mesh shielded wires.

The principle can be simply understood that the interference signal flows away through the shielding layer (aluminum foil, braided net) without contacting the communication signal, so as to achieve the purpose of anti-interference.

Post time: Sep-02-2022