Extech AUT100 Automotive Relay Tester.

Automotive Relay Tester
This quick go/no-go tester provides general health and functioning of common 4- and 5-pin automotive relays. It features Pass/Fail dual color LED (green and red) and three relay input configuration sockets (exposed pins only). It tests for: coil resistance, surge suppression device (resistor or diode), open/closed contact integrity (10 cycles), contact cyclic testing for intermittent failure detection, loaded contact continuity, relay contacts stuck open or closed, and time to contact closure and opening.