1. The car wiring harness does not choose the wire according to the regulation when changing the wire (the wire is too thin), the large pressure drop is generated when the large current passes through, and the wire skin is gradually aged and damaged;

2. Careless installation of battery, positive and negative polarity reverse connection, ac generator internal short circuit, each insulation shim and insulation sleeve damage, ac generator magnetic field wire and tie wire reverse connection will cause wire harness burn;

3. Car wiring harness is usually fixed with thin iron plate, whose edge is sharp like a knife edge, and there is no insulation on the surface of the metal plate. The vehicle vibrates and jolts in the long-term driving, and the power supply wiring harness is inevitable to be worn out, cut and put on the iron, causing the wiring harness to burn up;

4. When the car wiring harness is temporarily connected to the electrical equipment, it fails to make clear the current inlet and outlet of the fuse, that is, it randomly leads out the power cord, or after the fuse is burned out, it fails to change the fuse of the same specification as required, or it replaces the fuse with thick copper wire, losing its protective effect and burning the wire harness;

5. The two connected columns of ammeter often use plastic insulation sleeve, plastic heat dissipation, not only to withstand the current, but also to withstand turbulence and vibration, if the ammeter wiring loose or bad contact, will lead to a rise in temperature, resulting in plastic melting and tie iron, resulting in the wire bundle burned;

6. The connection of the connecting column is not reliable, resulting in a large pressure drop and heat. Over time, the insulation gasket will be damaged and the iron will be short-circuited. Note that the connecting post of ammeter and other instruments should be well connected. In addition, the connecting bolt of the wire fixed on the frame terminal plate should not be too long, so as not to burn the wire harness.