1. Disconnect the end of the coil wire from the distributor.
2. Use a well insulated tool (type of special pliers for ignition wires), to keep the end of the wire to be tested about 1 cm away from the metal housing of the motor.
CAUTION: Do not hold the wire with your bare hand. Use as much insulating material as possible between wire and tool. Do not stand at the moment of the spark test itself on a wet one. Do not touch the body of the car. The electric charge will go to the ground in the easiest way (with minimal resistance), make sure it's not you. It is necessary to choose a safe metal point for grounding near the end of the cable; do not select components that might contain liquids or wires.
3. Ask an assistant to crank the engine when the ignition is turned to the START position, but only for 1 or 2 seconds. If the end of the cable is at the correct distance from solid metal, a clear blue-white spark should jump when trying to start the engine.
4. Engine can be cranked for 1 or 2 seconds for flashes. A longer cranking process will force the fuel injectors to deliver fuel to the cylinders, causing the engine to prime, or in extreme cases, spark plugs.
5. If there is no spark, turn off the ignition and check the resistance of the lead wires to the coil, the voltage applied to the coil (12 V when on ignition), coil resistance, and air gap in the distributor.