1. Visual inspection method. When a part of the automobile electrical system fails, there will be smoke, sparks, abnormal noise, burning smell, high temperature and other abnormal phenomena. Through the sense of hearing, touch, smell and vision of human sensory organsAutomotive wiring harnessVisual inspection with electrical appliances, and then determine the location of the fault, greatly improving the speed of maintenance. For example, when the car line breaks down, abnormal phenomena such as smoke, sparks, abnormal noise, burning smell and high temperature often occur. Through visual inspection, the location and nature of the fault can be quickly determined.

2. Instrument inspection method. A method to diagnose automobile circuit faults by using comprehensive fault diagnosis instrument, multimeter, wave detector, current clamp and other instruments. For vehicles equipped with electronic control system, generally use the comprehensive fault diagnosis instrument to find the fault code and diagnose the fault range of the vehicle; Then use a multimeter, current clamp or wave detector to check the voltage, resistance, current or waveform of the relevant circuit, and diagnose the fault point of the car harness wire.

3. Tool inspection method. The lamp test inspection method is more suitable for checking the wire open circuit fault. When using the temporary test lamp method, it should be noted that the power of the test lamp should not be too large. When testing whether the control output terminal of the electronic controller has output and whether there is enough output, special attention should be paid to prevent the overload damage of the controller. It is best to use a diode test lamp.

4. Wire jumper inspection method. The jumper method is to use a wire to short the suspected faulty circuit, and then observe the change of the instrument pointer or the working condition of the electrical equipment to determine whether there is an open circuit or poor contact in the circuit. Jumper refers to the operation of connecting two points of two circuits with one wire. The potential difference between two points of the jumper circuit is zero, not a short circuit.