Abstract: A polarity and continuity tester of simple construction identifies grounded and positive lead wires in an automobile and is also capable of confirming proper operation of high voltage spark wires, all with one simple circuit. A tri-color light emitting diode is included in the testing device, along with a ground wire, a tester battery, a resistor and a conductive point probe, all connected in series. When the ground wire is secured to ground in the automobile, the point probe when touched to grounded conductors will cause the light emitting diode to emit a first color such as green, with current flowing through the diode in a first direction under influence of the tester battery. When the point probe is touched to a hot lead above about 5 volts, the tester battery becomes merely a conductor, current flows in the opposite direction, and the light emitting diode emits a second color such as red.