How to Diagnose Spark Plug Wires

Spark plug wires connect your vehicle's distributor to the spark plugs. When your spark plug wires begin to fail, you can experience a variety of problems including hard starting or stalling while the vehicle is running. To check whether or not your spark plug wires are the problem, you'll need to run a simple continuity test using a voltmeter. If your wires are bad, then you can replace them with new spark plug wires, which can be purchased at any auto parts store.

Things You'll Need

• Voltmeter

Instructions

1. Open the hood of your car and remove one of the spark plug wires from the engine. Pull the spark plug wire off the engine by pulling up on it. Then pull the other end of the spark plug wire off the distributor. Only remove and test one spark plug wire at a time.

2. Set the dial on your voltmeter to the "ohms" setting.

3. Place one of the leads from the voltmeter into one end of the spark plug wire. Then place the other lead from the voltmeter into the other end of the spark plug wire.

4. Check the readout on the voltmeter display. The resistance, measured in ohms, should be zero. A .05 variance is acceptable, however. If the reading falls outside of this range, your spark plug wires need to be changed.

5. Replace the spark plug wire and remove another one. Repeat Steps 3 and 4 until you have checked them all.

References

• "Auto Repair For Dummies;" Deanna Sclar; 1999
• "Automotive Tools Manual: Guide to Buying and Using Automotive Tools"; Thomson Delmar Learning; 1999