Testing the spark plug wires with a multimeter is a good way to verify that they are in good condition. When the spark plug wires fail, the car will hesitate, stumble, and shake, especially when going up a hill or under load. If the car runs especially poorly on a rainy day, that may be a sign that the plug wires are bad. Using a multimeter or ohmmeter will check if the wires are capable of delivering the required voltage to the spark plug, but a close inspection of the spark plug insulation and boots is also necessary.
Step 1: how to check spark plug wires with multimeter
Remove the cable to be tested. Please examine it carefully if it is a carbon wire, which is used in most household cars. This cable design generates heat due to its resistive qualities and can break over time. Look for heat marks, cracks, or insulation faults. If the cable is an import, it may have a winding design. This creates an inductive field around the wire that contains the interference. Inspect for similar faults.
Step 2: how to test spark plug wires with multimeter
Set the ohmmeter to the appropriate scale and measure the wire. For household wire, a good reading does not exceed 12,000 ohms per foot. This is on the higher end and quality cables will read 4,000 to 5,000 ohms per foot. Please refer to the repair manual for the specifications of the import plug cord. Test end-to-end cable with meter leads. Lead colors do not matter for this test: one at one end, one at the other end. Consider reading.
Lubricate the inside of the spark plug wire boot before installing it on the spark plug. Heat seals the boot onto the porcelain insulator and can make it difficult to remove. The boot release can be found at any auto parts store. Replace faulty cables before reinstalling. If two or more faulty cables are found on the vehicle under test, purchase and install a complete set.
Items you will need; how to test spark plugs with multimeter
- Measuring tape
- Spark plug boot release