GSI 4800 Computer-Safe 12-Volt Circuit Tester

The GSI 4800 Computer Safe Circuit Tester is a specialized 12-volt diagnostic tool engineered for use on modern vehicle electrical systems—particularly safe for sensitive electronic control modules. When connected, the tester’s LEDs display polarity: red when the clip is on ground and the probe touches positive, and green when the clip is on positive and the probe touches a ground point. Its design prevents damage to onboard computers and modules during circuit testing.