GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 39200 Digital Multimeter

  1. Disconnect both ends of each spark plug wire you are testing.
  2. Ensure that the wire terminals are clean before proceeding.

  3. Use the J 39200 .
  4. Connect an ohmmeter lead to each end of the wire.
  5. Gently twist the wire while watching the ohmmeter reading.
  6. If the ohmmeter reads above 30,000 ohms, no matter how long the wire is, or fluctuates from infinity to any value, replace the wire.