The OTC 3415 is used for diagnosing electrical faults and CAN bus line activity. Check power and ground circuits, check active protocol lines, or connect a multimeter or oscilloscope for detailed signal analysis. Connect, detect, monitor voltage and more; It connects between Diagnostic Link Connector (DLC) and scan tool. It detects data and protocol communication and monitors system voltage with a display and high/low alarm. Connect leads for increased diagnosis, analysis, and monitoring. Useful Functions Include: Verifying 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; Alarm warning when voltage drops below 11.6v or rises above 15.2v.