Abstract: An instrument for performing electrical tests includes a housing adapted to be held in the hand. A conductive probe and a two-conductor power cable adapted to be connected to a vehicle battery protrude from the housing. Red and green light emitting diodes (LED's) mounted in the housing are operatively interconnected with the probe and power cable through circuitry which causes the red LED to glow when the probe contacts a positive voltage, and the green LED to glow when the probe contacts a low voltage, ground, or a negative voltage. Continuity testing may be performed by contacting the probe against one terminal of a device to be tested, and contacting the other terminal of the device to ground or to an auxiliary test lead extending from the housing, causing the green LED to glow. The instrument includes a momentary contact switch that permits the probe to be energized by internal connection to the positive or ground input terminal.