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A spark plug tester is a handy tool that allows you to check if your spark plug is working properly. It can also save you time by allowing you to check if the problem is actually in your ignition.
Regarding this, what does a spark plug tester look like?
The spark ignition tester connects to the boot the same way the boot connects to the spark plug itself. It will usually look like a clear cylinder with a wire coil and a light bulb inside.
Similarly, it is asked, how do you check a spark with a test light?
Attach the test light to a good engine ground. With the engine running, move the test light along the length of each spark plug wire. If a spark jumps from a plug wire to the test light at any point, this is an indication that the insulation has broken down, and the spark plug wire should be replaced.
The ignition coil is what generates the spark, so if it's present at the right times but weak, the coil is usually to blame. It is a voltage amplifier. If only a portion of the coil inside it shorts, it will partially amplify the voltage so the spark will be weak.