Detecting automotive circuit faults requires a combination of multiple professional methods. First, conduct a visual inspection to check if wire harness connectors are loose, if wire insulation is burned, or if electrical components are obviously damaged. Corrosion on battery terminals should be addressed promptly. Use a digital multimeter to measure resistance and voltage, focusing on testing the ignition coil, generator, and fuel injector circuits. Abnormal voltage (e.g., generator output below 13.8V or battery voltage less than 12.4V) may indicate a fault. The test light method can quickly verify circuit continuity: connect the test light to the suspected fault point, and the on/off status can determine power supply or grounding issues. For complex faults, connect the original equipment manufacturer (OEM) diagnostic tool to read fault codes (such as Pxxxx codes) and analyze abnormal module power supply or sensor signals in conjunction with circuit diagrams. The spark test method can be used for high-voltage circuits; if the spark is weak or absent, check the ignition system components. Follow the principle of static before dynamic during operation: inspect basic circuits with power off first, then observe changes in phenomena with power on. Pay attention to safety protection: connect a fuse in series when measuring high-voltage circuits to avoid short circuits that damage equipment. Systematic troubleshooting can efficiently locate faults, from simple fuse checks to in-depth schematic analysis, gradually narrowing the scope to ensure precise maintenance.
