How to Check Vehicle Circuit Faults?

[Frederick]

Methods for checking vehicle circuit faults include: 1. Visual Inspection: Determine the fault range by observing surface phenomena such as car instruments, indicator lights, and circuit connections; 2. Spark Test: While driving or without instruments, test by grounding wires or terminals to the car body, or touching wires to terminals to observe if sparks are generated, thereby judging current supply and continuity; 3. Testing Method: Use instruments to test circuits or components to determine faults; 4. Replacement Method: Replace components or wires to identify faults; 5. Spark Plug Test: When it is confirmed or suspected that a certain engine cylinder is malfunctioning, use the spark plug test method. That is, while the engine is running, disconnect the high-voltage wire from the spark plug of that cylinder, leaving a 5mm to 7mm gap, and perform a "spark test". If the engine performance significantly improves, it indicates the spark plug is faulty. If there is no improvement, replace the spark plug.