How to Test Spark Plug Wire Resistance

By Kurt Schanaman
Spark Plug Wire Resistance
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All electrical components in circuits have a specific amount of resistance to electrical flow, and spark plug wires are no different. The amount of resistance can be too low for some applications, while too high for others. But in the case of spark plug wire resistance measurements, the goal is generally to determine only if there is a short or a break in the wire rather than for efficiency reasons. Luckily, a low-cost multimeter from the electrical department of any department store will perform this needed test with little difficulty.

Step 1

Insert the black-wired multimeter cable into the negative (-) jack of your meter and insert the red-wired multimeter cable into the positive (+) jack of your meter.

Step 2

Turn on your multimeter and set the measurement-type dial to measure ohms. Touch the tips of the test cables together while looking at the display on your meter to ensure the meter is functioning correctly. When touching the two tips together, the meter should read 0.000 on a digital meter, and just 0 on an analog meter.

Step 3

Touch the tip of one test probe (either one) to the metal plug on one end of your spark plug wire and then touch the tip of the other test probe to the metal plug on the other end of the spark plug wire. Make sure the test probe tips are both touching the metal ends of the spark plug wire at the same time in order to get a reading.

Step 4

Check your meter's display to determine if the spark plug wire is good. The meter will read a defined number of ohms if the wire is good, but if the wire is broken inside the spark plug wire, a digital meter will show a "1." on the display indicating loss of continuity due to a wire break. On an analog meter, a broken wire will be indicated by the needle swinging to "open." For spark plug wires, if there is no ohm value being displayed, discard the wire and replace with a new one.