<p>Designed for quick and easy diagnosis ignition/engine issues or a fault in the fuel delivery system. Simply connect the tester inline between the spark plug and the plug wire, if a spark is being sent, the tester will mirror the spark and light up. The flashing indicator light clearly identifies potential issues with the ignition system.</p><br/><h4>Testing Method:</h4><br/><ol><br/><li>Turn off the engine and disassemble the spark plug coil.</li><br/><li>Connect the black leather of the tester to the spark plug.</li><br/><li>Connect the metal end of the tester to the spark plug coil.</li><br/><li>Start the engine.</li><br/><li>The weak ignition wire is intact and the indicator light flashes.</li><br/></ol>