Turn off the ignition and disconnect the battery negative terminal
Locate the ignition coil and disconnect all electrical connectors
Remove the coil from the vehicle if needed for easier access
Set the ohmmeter to the lowest resistance range
Measure primary resistance by placing the meter probes on the coil’s primary terminals
Compare the primary resistance reading to the manufacturer’s specification
Measure secondary resistance by placing one probe on a primary terminal and the other on the high-voltage output terminal
Compare the secondary resistance reading to the manufacturer’s specification
Check for an open circuit by looking for infinite resistance
Check for a short circuit by looking for very low or zero resistance where it should not be present
Inspect the coil for cracks, burns, or corrosion
Reinstall the coil and reconnect all connectors after testing
Reconnect the battery negative terminal
Replace the ignition coil if the readings are outside specification