Secondary Spark Test

Secondary Spark Test

This spark tester looks just like a spark plug. Attach the clip to ground and crank the engine to check for spark.

This spark tester has an adjustable air-gap for measuring spark strength and testing different voltage ignition systems.

Attach the clip to ground then crank the engine to check for spark.

This spark tester is the easiest to use. Just place it on a plug wire and the spark voltage is detected; the bulb on the top will flash with each pulse.

NOTE: The best way to perform this procedure is to use a spark tester (available at most automotive parts stores). Three types of spark testers are commonly available:

The Neon Bulb type is connected to the spark plug wire and flashes with each ignition pulse.
The Air Gap type must be adjusted to the individual spark plug gap specified for the engine.
The last type of spark plug tester looks like a spark plug with a grounding clip on the side, but there is no side electrode for the spark to jump.

NOTE: The last two types of testers allow the user to not only detect the presence of spark, but also the intensity of the spark. Orange/yellow is weak, blue is strong.

Disconnect a spark plug wire at the spark plug end.
Connect the plug wire to the spark tester and ground the tester to an appropriate location on the engine or frame.
Crank the engine and check for spark at the tester.
If spark exists at the tester, the ignition system is functioning properly.
If spark does not exist at the spark plug wire, perform a diagnostic test of the ignition system using individual component diagnosis procedures.