What Is the Way to Test a 12-Volt Ignition Coil?
In order to test the spark, pull the spark plug from the engine, and then start the car. There should be a bright blue spark between the electrodes every time the cylinder fires, provided that there is enough voltage reaching the spark plug. The coil is likely to be faulty if there is no spark.
A digital multimeter is required for testing the resistance levels of the ignition coil. The terminals of the coil are going to be marked "negative" and "positive," and these are the two points where the resistance of primary winding can be measured.
Step 1: Prepare the multimeter
To check a 12 volt coil, set the multimeter to at least a 200 Ohms setting. Attach both leads of the meter to the coil-terminals with black to the negative terminal and red to the positive one.
Step 2: Test the resistance
The normal, acceptable range for a standard 12-volt car is 1.5 to 1.7 Ohms. See if the reading is within this range.
Step 3: Test the secondary coil resistance
Set the meter to 20K Ohm setting, and attach the leads to the ignition coil's center terminal. The reading for secondary-coil resistance should be 11, because if it is lower, that's the reason why sparks are not appearing.