Plug these testers into any car connector and you will have an instant test of running light circuits. Features LED display to show completed circuit for the running lights, left turn signal and right turn signal. Auxiliary and electric brake circuit are included on the 6-way tester and auxiliary, electric brake and battery charge are included with the 7-way tester. One piece units with internal ground. Proper installation and set-up of a brake control, when a trailer is not readily available, is possible with the 7-way tester.Current Monitor testing device is designed to assist in determining whether a tow vehicle's 7-way blade car end connector has been wired properly. (Current Monitor is an excellent diagnostic tool for installation, setup and troubleshooting of electric trailer brake controls.)The Trailer Tester is designed to help you quickly identify problems in the wiring of the trailer. This is done by testing the Left Turn, Right Turn, Tail/Marker, Brake and Back Up circuits on the trailer. The tester indicates approximate amount of current in each circuit. It will also test the voltage of the external battery connected to the trailer charge circuit (i.e. trailer battery).Brake Control Bench Tester is a test device designed to determine if a brake control is working properly. Checks brake control output, independent of vehicle wiring. Simulates many fault conditions including open ground, short circuit, open load and more.