The CTB features an intuitive inlay panel to aid in the diagnostics of vehicle DLC circuits and CAN bus systems operation. How? All LEDs correspond to vehicle DLC pins 1-16. The inlay panel features DLC pin number and description for quick identification.All LEDs are color coded for easy and fast identification. They light up with DLC pin signal activity, giving you an instant indication of functionality.Separate Power ‘ON’ LED confirmation for quick confirmation that the unit is operating.Pass Thru capability for OEM and aftermarket scan tools.