7-Way RV Blade Trailer Light Wiring Circuit Tester Round Adapter Pin Plug UK

12V:Auxiliary(12V+)(Tester should stay lit at a constant). 7 WAY TESTER. TM: Taillights(Turn on running lights.Tester should stay lit at a constant). Plug the tester into vehicle's mating plug. BU:Back up(Shift vehicle into reverse.Tester should stay lit at a constant).

eBay