What are the diagnostic methods for automotive ignition system failures?
2 Answers
Automotive ignition system failure diagnostic methods are as follows: 1. Ignition coil fault detection method: Use a multimeter or test light to connect to the "+" terminal of the ignition coil. If the terminal has power, it indicates the ignition coil is functioning normally. If there is no power, it may be due to poor contact of the ignition switch or a short circuit in the wire between the ignition switch and the "+" terminal of the ignition coil. 2. Spark plug burnout: If the top of the spark plug is scarred, eroded, or melted, it indicates the spark plug is damaged and needs replacement. 3. Spark plug deposits: Excessive deposits on the top of the spark plug can cause the engine to malfunction.
I've been repairing cars for over a decade and have dealt with numerous ignition system failures. When diagnosing, I usually start with the basics: First listen for sounds - if there's no clicking noise when starting, it might be a starter or battery issue. Test the battery voltage - it should be above 12 volts; if lower, it needs charging or replacement. Then check the spark plugs by pulling one out and grounding it to metal to see if there's a spark. No spark could indicate a failed coil or broken high-voltage wire. For modern vehicles, use an OBD scanner to read fault codes - for example, P0351 indicates an ignition coil problem. Also need to check the crankshaft sensor signal, as failure can cause complete failure to start. The whole process should be done slowly and steadily, with a multimeter being essential. Stay safe and avoid electric shocks. Ignition system failures left unrepaired will affect engine performance and may even double fuel consumption, so when noticing symptoms like shaking or slow acceleration, it's best to check early to avoid bigger troubles.
