1. Insert the banana plug at one end of the testing wire into top metal cap of the neon-electroscope and ensure sound contact
2. Clip the alligator clip at the other end of the testing wire to the grounding(i.e.the automobile's metal casing).
3. Insert the electroscope's needle head into insulation of the wire to be measured
4. A lit lamp in the pen arm indicates a loop (or complete circuit) has been established at the testing point, and the service is normal.