Appearance inspection 1) The new wire harness model should be the same as the original model, the wire terminals and the wires are connected reliably, and the connectors and wires can be pulled by hand to check whether there is looseness or detachment. 2) Compare the new wiring harness with the original wiring harness, such as: the size of the wiring harness, wire terminal connectors, and wire color should be basically the same. If in doubt, use a multimeter to test and confirm that the wiring harness is intact before replacing it.
The connectors, plugs, and sockets for installing all electrical equipment must correspond to the sockets and plugs on the wiring harness. After connecting the connecting wires to the electrical equipment, leave a certain amount of allowance. The wires must not be pulled too tightly or loosely.
Inspection of wiring 1) Inspection of wiring After the wiring harness is replaced, first check whether the wiring harness connector is correctly connected to the electrical equipment, and whether the battery positive and negative terminals are connected correctly. 2) The ground wire of the battery can be temporarily disconnected during the power-on test. Use a 12V, 20W bulb as the test lamp, and connect the test lamp in series between the battery negative terminal and the frame iron end, and turn off all electricity in the car. Device switch. The test lamp should not be on when it is normal, otherwise the circuit is faulty. When the circuit is normal, remove the bulb and use a 30A fuse in series between the battery negative terminal and the frame ground end. Without starting the engine, turn on the power of each electrical device on the vehicle one by one. And circuit inspection, after confirming that the electrical equipment and wiring are not faulty, remove the fuse and connect the battery ground wire. The common specifications of the wires in the wiring harness are the nominal cross-sections of 0.5, 0.75, 1.0, 1.5, 2.0, 2.5, 4.0, 6.0 and other square millimeter wires. Each of them has a permissible load current value, which is suitable for electrical equipment with different power wire. Take the vehicle wiring harness as an example. The 0.5 specification line is suitable for instrument lights, indicators, door lights, ceiling lights, etc .; the 0.75 specification line is suitable for license plate lights, front and rear small lights, brake lights, etc .; the 1.0 specification line is suitable for turn signals, fog. Lights, etc .; 1.5 size wires are suitable for headlights, horns, etc .; main power lines such as generator armature lines, ground wires, etc. require 2.5 to 4 square millimeters of wire. This only refers to the general car. The key depends on the maximum current value of the load. For example, the ground wire of the battery and the positive power line are used exclusively by automobile wires. Their wire diameters are relatively large, at least a dozen square millimeters. Above, these "Big Mac" wires will not be programmed into the main harness. Before you arrange the wiring harness, you must draw a wiring harness diagram in advance. The wiring harness diagram is different from the circuit schematic. The circuit schematic is an image that expresses the relationship between various electrical parts. It does not reflect how electrical parts are connected to each other, and is not affected by the size and shape of each electrical component and the distance between them. The harness diagram must take into account the size and shape of each electrical component and the distance between them, and also reflect how the electrical components are connected to each other. After the technician at the wiring harness factory made the wiring harness wiring board according to the wiring diagram, the workers cut the wiring according to the rules of the wiring board. The vehicle main wiring harness is generally divided into engine (ignition, EFI, power generation, starting), instrumentation, lighting, air conditioning, auxiliary electrical appliances and other parts. There are main wiring harness and branch wiring harness. A vehicle main harness has multiple branch harnesses, just like tree poles and branches. The main wiring harness of the whole vehicle often uses the dashboard as the core part and extends forward and backward. Due to the length relationship or the convenience of assembly, some automobile wiring harnesses are divided into head harnesses (including instruments, engines, front light assemblies, air conditioners, batteries), rear harnesses (tail light assemblies, license plate lights, luggage compartment lights), canopy roofs, etc. Harnesses (doors, ceiling lights, audio speakers), etc. Each end of the wire harness is marked with a number and letter to indicate the connection object of the wire. The operator sees that the mark can be correctly connected to the corresponding wire and electrical device. This is particularly useful when repairing or replacing the wire harness. At the same time, the color of electric wires is divided into single-color wires and two-color wires, and the use of colors is also specified, which is generally a standard customized by the car factory. China's industry standards only stipulate the main color, for example, a single black color is dedicated to ground wires, and a red monochrome color is used for power lines, which should not be confused. The wire harness is wrapped with woven thread or plastic adhesive tape. For safety, processing and maintenance convenience, woven thread wrapping has been eliminated and is now wrapped with adhesive plastic tape. The connection between the wiring harness and the wiring harness, and between the wiring harness and the electrical parts adopts a connector or a wire lug. The connector is made of plastic and has a plug and a socket. The wire harness and the wire harness are connected by a connector, and the connection between the wire harness and the electrical parts is by a connector or a wire lug.