What are the methods for automotive circuit maintenance and inspection?

[OKeira]

Here are the methods for automotive circuit maintenance and inspection: 1. Visual Diagnosis Method: When a car circuit malfunctions, abnormal phenomena such as smoke, sparks, unusual noises, burnt smells, or overheating may occur. These phenomena can be directly observed to determine the location of the fault. 2. Open Circuit Method: When a short circuit (grounding) fault occurs in automotive circuit equipment, the open circuit method can be used for judgment. By disconnecting the suspected circuit section and observing whether the grounding fault persists in the electrical equipment, the location and cause of the circuit grounding can be determined. 3. Short Circuit Method: For open circuit faults in automotive circuits, the short circuit method can also be used. This involves short-circuiting the suspected open circuit section with a screwdriver or wire and observing changes in the instrument pointer or the working condition of the electrical equipment to determine if there is an open circuit fault. 4. Test Lamp Method: This method uses an automotive bulb as a test lamp to check for open circuit faults in the circuit. 5. Instrument Method: Observe the indications on the car's instrument panel, such as the ammeter, water temperature gauge, fuel gauge, and oil pressure gauge, to determine if there is a circuit fault. For example, if the water temperature gauge shows full scale and does not move when the ignition switch is turned on with the engine cold, it indicates a fault in the water temperature sensor or a grounding in the circuit. 6. Low-Voltage Grounding Spark Test Method: This involves removing a wire from the electrical equipment and touching it to the car's metal part (grounding) to produce sparks for judgment. This method is relatively simple and commonly used by automotive electricians. The grounding spark test can be divided into direct grounding and indirect grounding. Direct grounding produces strong sparks without passing through a load. For example, to check if the circuit from the ignition coil to the battery is faulty, disconnect the wire connecting the ignition switch from the ignition coil and scrape it against the car body or frame. If there are strong sparks, the circuit is normal; if not, there is an open circuit. Indirect grounding produces weak sparks through a load to determine if there is a fault in the circuit or load. For example, grounding the connection wire of a traditional ignition system breaker. If sparks occur, the circuit is normal; if not, there is an open circuit. It is important to note that the spark test method should not be used on electronic circuit vehicles. 7. High-Voltage Spark Test Method: Perform a grounding spark test on the high-voltage circuit and observe the spark condition to judge the working condition of the ignition system.

[LylaAnn]

With over a decade of auto repair experience, I've learned that wiring inspections require methodical steps: First, disconnect power and check fuses by pulling them out one by one to examine burn marks. Second, use a multimeter to test continuity, focusing on grounding points and power terminal voltages. Third, trace wiring harnesses by hand, addressing any exposed or aged insulation immediately. Finally, inspect controller connectors for scorch marks or looseness. The key is using a test light to locate short circuits, then peeling back harness tape to check for copper wire oxidation. If wiring gets wet, dry it thoroughly before insulating, and spray connector pins with rust remover. These jobs are best done with interior panels removed—always keep a flashlight and electrical tape handy.

[LiamRose]

Tips I learned from modifying my car audio system last time: First, distinguish between signal wires and power wires during circuit inspection. Use a 12V test light or diode tester to quickly locate faulty sections. For relay contact carbon buildup, simply sand it with sandpaper. The key is to follow the circuit diagram—for example, wires in door corrugated tubes are prone to breakage, and engine bay wiring harnesses should avoid contact with the exhaust pipe. Take photos of connector positions before unplugging to avoid incorrect reassembly. Don't use regular tape to patch rodent-chewed holes—opt for waterproof heat-shrink tubing instead. Parking away from damp grass daily can slow down wire aging.