PowerScan PS100 Features： Performs every type of service including power injection, measurement, ground testing, polarity checks, continuity testing and components activation With a flip of the power switch, you have an instant hot/ground lead for powering up electrical components like cooling fans, relays, etc. Simultaneously uses the hot lead and the ground lead to activate components right in your hand Instantly identifies positive, negative and open circuits Tests for bad ground contacts instantly, allowing you to follow and locate shorts fast without wasting fuses Instantly checks continuity of switches, relays and diodes Circuit breaker protected Audio tone indicator allows for no-look menu scrolling once users are familiar with menu tone assignment.