Connects between diagnostic link connector (dlc) and scan tool alarm warning when voltage drops below 11.6v or rises above 15.2v connect leads for increased diagnosis, analysis, and monitoring leds at pin-out display signal detection, flashing leds for ecu activity check power and ground circuits use this tool for diagnosing electrical faults and can bus line activity. check active protocol lines, or connect a multimeter or oscilloscope for detailed signal analysis. useful functions: verify ecu activity, leds at pin-out display signal detection, flashing leds for ecu activity monitoring of obdii data lines probe lines with scope or multimeter for detailed signal information check and monitor battery voltage, continuous numeric display or voltage