How to Test Plug Wires With an Ohmmeter

Ohmmeters or multimeters on the "ohm" setting are used to test spark plug wires for deficiencies. When set to ohms, the device measures the resistance present in the wires. Foreign and domestic cars have specific ranges that the wire resistance must fall between for the spark plug to work properly. Some common symptoms of faulty plug wires are halting or jumpy movements and poor performance on wet days.

• 1

  Plug the testing leads into the multimeter. Insert the black lead into the ground (common) port and the red lead into the volt/ohms port.

• 2

  Set the multimeter to "ohm." Consult the vehicle service manual for additional scale settings.

• 3

  Remove the wire or wires you wish to test.

• 4

  Touch one of the leads to one end of the wire and the other lead to the other end. The order is not important in this testing exercise.

• 5

  Write down the reading. Consult the vehicle service manual to determine the normal range of resistance for your model. Replace the wire if it does not meet the recommended standards. Repeat the test for each wire if necessary.