Spark Plug Wire Tester

For easy testing of spark plug wires. Inductive design.Tester lights up when electrical current is detected. -Fasten alligator clip end of spark plug wire tester to vehicle ground -Position receptacle end of spark plug wire tester over spark plug wire -With engine running, observe clear window in spark plug tester -Light flashing indicates sound wire -No flashing light indicates unsound wire or spark plug or connection