How to check an ignition coil

The ignition coil is a vital component of the ignition system in a vehicle. Its main function is to transform the low voltage from the battery into the high voltage needed to create a spark in the spark plugs. A faulty ignition coil can cause various ignition-related issues such as misfires, rough idling, and difficulty starting the engine. Hence, it is important to regularly check the ignition coil to ensure it is working properly. In this article, we will discuss how to check an ignition coil.

Before beginning the process, ensure that the engine is turned off and has cooled down completely. Also, make sure you have the necessary tools such as a multimeter, insulated pliers, and a service manual specific to your vehicle.

Step 1: Locate the Ignition Coil
The ignition coil is usually located near the engine, attached to the engine block or the cylinder head. Refer to your vehicle’s service manual to locate the ignition coil.

Step 2: Disconnect the Ignition Coil
First, disconnect the negative terminal of the battery to prevent any electrical mishaps. Then, locate the primary and secondary wires connected to the ignition coil. The primary wire is typically thinner and connected to the distributor or the ignition module. The secondary wire is thicker and connected to the spark plugs. Carefully disconnect both wires from the ignition coil using insulated pliers.

Step 3: Test the Primary Circuit
The primary circuit of the ignition coil is responsible for receiving and transferring low voltage from the battery. Set your multimeter to the resistance or ohms setting. Connect one lead of the multimeter to the positive terminal of the coil and the other lead to the primary wire that was disconnected from the coil. A reading within the range specified in the service manual indicates a healthy primary circuit.

Step 4: Test the Secondary Circuit
The secondary circuit delivers high voltage to the spark plugs. Set your multimeter to the voltage setting. Connect one lead to the positive terminal of the coil and the other lead to the secondary wire that was disconnected from the coil. Ask an assistant to crank the engine while you observe the multimeter. A voltage reading within the specified range indicates a functional ignition coil.

Step 5: Check for Physical Damage
Inspect the ignition coil for any signs of physical damage such as cracks, corrosion, or melted wires. If any damage is found, it is recommended to replace the ignition coil.

Step 6: Consult a Professional
If your multimeter readings are not within the specified range or if you are unsure about the readings, it is advised to consult a professional mechanic. They have the expertise to accurately diagnose and resolve any issues with the ignition coil or the ignition system.

Regularly checking the ignition coil is crucial for maintaining a properly functioning ignition system. By following these steps, you can easily test your ignition coil and identify any potential problems. If any issues are detected, it is important to address them promptly to ensure optimal engine performance and prevent further damage.