The 4/5 Pin Trailer Harness Checker traces each lighting function to the terminal in question. After plugging into the trailer plug, each LED light will correspond to the circuit being energized, allowing the technician to easily diagnose trailer malfunction. The 4/5 Pin Trailer Harness Checker traces each lighting function to the terminal for trailer lighting setups.

Warning: This product may expose you to chemicals including lead which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov