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How do I test the ignition coil?

How do I test the ignition coil?

The ignition coil is an essential part of a vehicle's engine. It is responsible for producing the sparks needed to ignite the fuel and create the combustion that powers the engine. The latter is a critical component because it can be the cause of an engine that won't start. That's why it's important to check the ignition coil from time to time to make sure it's working properly. To be sure of the condition of your ignition coil, you can still test its condition by performing a resistance or spark test. Testing the ignition coil is relatively simple and can be done at home if you have the proper tools.

How can I tell if my ignition coil is bad?

There are several signs of a bad coil. Here are some of the more common symptoms:

  • Engine Won't Start: If the ignition coil is defective, it may not provide enough power to the spark plug to ignite the air-fuel mixture in the combustion chamber, making it difficult to start the engine.
  • Misfiring: If the ignition coil does not provide sufficient voltage, the spark plug may not produce a spark strong enough to ignite the air-fuel mixture. This can cause misfiring, loss of power, engine knock, or knocking noises.
  • High fuel consumption: If the ignition coil is defective, the air-fuel mixture may not burn properly in the combustion chamber, resulting in excessive fuel consumption.
  • Warning Lights Illuminated: In some cases, an ignition coil malfunction may cause an engine warning light to illuminate on the vehicle's instrument panel.
  • Power loss: If the ignition coil is not working properly, the engine may lose power, making it difficult to drive the vehicle.
  • Engine light illuminates
  • Opaque smoke when starting

How to test your ignition coil?

Solution 1: Resistance test

  1. First, make sure the engine is turned off and the key is removed from the ignition.
  2. Locate the ignition coil. On most vehicles, it's located near the engine, usually on top of the cylinder block.
  3. Disconnect the wires connected to the coil. Make sure you know where they are so you can reconnect them properly later.
  4. Use a multimeter to measure the resistance of the coil. Set the multimeter to the ohms (Ω) scale and place the probes on the ends of the ignition coil terminals. Consult the vehicle manufacturer's specifications for the appropriate resistance range. If the resistance is outside this range, it may indicate a problem with the coil.
  5. Check the coil's internal continuity. Set the multimeter to the ohms (Ω) scale and place one probe on one end of the coil and the other probe on the other end. If the resistance reading is infinite (OL) or very high, this may indicate an open internal circuit in the coil.
  6. Inspect the coil for visible signs of damage or corrosion. Physical damage or excessive corrosion may also indicate a problem.

Solution 2: Spark test without a multimeter

  1. Stop the engine and raise the hood. Open the hood and locate the coil. The coil is usually located next to the bumper, near the starter, or under the distributor head. On cars without distributors, the spark plugs are connected directly to the coil.
  2. Remove the wire from one of the spark plugs. Next, remove the wire from one of the spark plugs. Normally, the wires are used to connect the spark plugs to the coil.
  3. Use a spark plug wrench to remove the spark plug. Once you've removed the cable, remove the spark plug itself.
  4. Reconnect the spark plug to the coil using the power cable. Carefully replace the spark plug lead. You must have a spark plug connected to the distributor. Handle the spark plug with insulated pliers to avoid electric shock.
  5. Place the threaded end of the spark plug against a metal part of the engine. Then manipulate the spark plug, still connected to its lead, so that the threaded end touches a visible metal part of the engine.
  6. Remove the fuel pump fuse. Before starting the engine to test a spark plug, turn off the fuel pump.
  7. Ask a friend to start the engine. Have a friend or helper turn the starter key.
  8. Watch for blue sparks. If the ignition coil is working properly, you should see a blue spark between the spark plug electrodes as your friend turns the engine over.
  9. Carefully reinstall the spark plug and power cord. At the end of your test, make sure your vehicle's engine has stopped before repeating the previous steps in reverse order.

It's important to note that test procedures may vary slightly depending on the vehicle model and type of ignition coil used. It is therefore advisable to consult your vehicle's owner's manual or seek the assistance of a qualified professional if you are unsure of the procedure to follow.

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