Traditionally, in order to check if the electrical signals from your truck to your trailer were working, you’d need a second person to relay back the information to the operator. Thanks to the innovative STEELMAN PRO 78922 Bluetooth Trailer Tester you can quickly and efficiently test the signals by yourself. The tester plugs right into the 7-pin flat / blade trailer connector found on the back of trucks and towing vehicles. A free downloadable app allows Bluetooth enabled smart devices / phones to connect to the tester and display tested signals and shows you if any are malfunctioning. This tool can test brake lights, running lights, reverse lights, turn signals, and even electric trailer brakes and 12V charge lines. These helpful features allow you to quickly diagnose and fix the exact malfunction, which in turn keeps you and other drivers safe on the road.