Curt Manufacturing Led 4-flat tester

A connector tester works by plugging into the connector socket on your vehicle and responding to the various electrical signals produced by pushing the brake pedal, signaling a turn, turning on the running lights and so on. When the socket is getting proper power, the testers various LEDs will light up corresponding to each wire in the connector. Testing your vehicle-side socket is essential after installing a new custom vehicle-to-trailer wiring harness and is highly recommended every time you hitch up to tow. Also, if you are experiencing electrical problems with your trailer, a CURT tester will be able to tell you whether the problem is rooted in your vehicles electrical system or if your trailer needs some rewiring.