How to Diagnose Faults in a Car's Ignition System?
2 Answers
Diagnostic methods for faults in an electronically controlled ignition system are as follows: 1. Electronically controlled ignition system: Typically, an ignition coil consists of two main coils—the primary coil and the secondary coil. These two coils play a key role in ignition by converting voltage from low to high. Since the primary coil has more turns than the secondary coil, the ignition coil can transform the vehicle's low voltage into high voltage. 2. Principle: When current is conducted to the primary coil, electrical energy is converted into magnetic energy within the primary coil, gradually forming a strong magnetic field around the coil, which stores the magnetic energy in the coil's iron core. Generally, the coil is equipped with a switching device. When the switching device disconnects the primary coil's circuit, the magnetic field rapidly decreases due to the absence of current, and the secondary coil, having fewer turns, induces a very high voltage. Understanding this principle allows for diagnostic troubleshooting when a fault in the ignition system is initially suspected.
When I encounter ignition system issues while repairing a car, such as the engine failing to start or jerking after starting, I start with the simpler checks. I usually first inspect the spark plugs. If they are burnt out or the gap is incorrect, the spark won't ignite; old spark plugs or excessive carbon buildup can also affect ignition. Next, I check the ignition coil—if it's aged, it may cause weak or no spark. The wiring connections also need a look, as sometimes wires can age, short-circuit, or become loose. Low battery voltage could also be the culprit, so I use a multimeter to check if it's above 12 volts. If all these are normal, the issue might be a faulty computer module, which requires an OBD scanner to read the fault codes. I've managed to fix it myself a few times, but if I can't figure it out, I take the car to the repair shop immediately—prolonged ignition problems can harm the engine.
