The Hopkins Tow Doctor Trailer Wire Harness Test Unit, No. 50928, is designed so that one person can make sure a trailer has been wired properly and all functions are working. This tool tests all trailer functions: left turn, brake, tail, backup lights; electric brakes and auxiliary power, and adapts to 4-Wire Flat, 6-Pole Round, or 7 RV Blade. Trailer lights illuminate and LED lights on the tester show function operation, and the amperage meter shows actual amp draw. For electric brakes, magnets are activated to determine correct operation. The unit includes battery terminal clips and can be used with any 12V battery.
