The J-OK makes it easy for engineers and non-engineers alike to visually verify the behavior of an available vehicle data port. Designed for the standard 9 pin circular J1939 connector, the integrated LEDs on this device indicate the presence of vehicle power, correct power polarity and the presence of CAN activity at any valid J1939 bitrate. This tool provides a quick check to make sure everything is ready-to-go prior to a DAP installation or to troubleshoot any connection issues.