How to Check for Ignition Spark

An engine's ignition system is responsible for igniting the fuel-air mixture inside the combustion chamber and when the ignition process stops the engine will not run. Testing for spark is an easy process, there are a few things you should know before beginning which we have described in the following guide and video. This test will help you determine if the entire ignition system is down or if a particular cylinder is not working. If you have any ignition spark questions please ask our experts for free.

Let's Jump In!

If the engine is not running choose the easiest spark plug wire or ignition coil to remove, or if you have a cylinder that is not producing power this guide will work. Here we have removed the ignition coil of the #2 cylinder and exposed the output terminal which connects to the spark plug.
ignition coil output terminal

Use a piece of wire that has a small piece of the insulation removed on both ends, attach one side of the wire to a good ground source, either on the engine or to the negative side of the battery.
ground connection

Using a clamp, position the exposed wire end away from the coil output terminal creating an air gap about the width of a pencil. This shows the coil output connector easily exposed, if that is not the case for your application simply bend the wire down into the coil or spark plug wire boot while retaining the air gap.
air gap

In this next image we have turned the lights off so you can see the ignition spark more clearly. Before you test for spark keep your fingers away from the wire and output terminal to avoid accidently getting zapped, (this is not enough to cause bodily harm, but it can sting a little). Crank the engine over and observe the air gap, there should be a visible spark if the ignition system is working. If the engine is running and you are checking a cylinder misfire or to see if the coil is working it's okay to allow the engine to run, again stand clear of the engine for this test.
ignition spark

Watch the Video!

Please watch this video of the job being done, then continue with your ignition system test guide to glean additional helpful information.


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