Features:1. This tester has one side to connect the 7-pin plug of a trailer and another side to connect the 7-pin socket of a car, very convenient.2. Ergonomic design of the 7-pin trailer socket ensures high-performance operation.3. This trailer tester helps quickly check circuit failures in vehicles and trailer electrical systems.4. Made of ABS plastic and copper, durable with a long service life.5. Ideal for commercial and private use, suitable for workshops, car and trailer rentals, and accessory trade.Specification:Main Material: ABS & CopperColor: BlackItem Type: Diagnostic ToolsItem Name: Trailer TesterSize: Approx. 20 x 5 x 4cmBattery Type: 9V (not included)Package Size: 20 x 5.5 x 4.5cm / 7.9 x 2.2 x 1.8inPackage Weight: 194g / 6.8ozPackage List:1 x 7-Pin Trailer Tester ToolFunction & Guide:Trailer (can also be a caravan or bicycle carrier)Insert the plug into the connection of the tester.Press the yellow button on the side of the tester.If the wiring is good, all the LEDs light up. The function of each LED is as follows:1. Left hand indicator (yellow);2. Foglight or 12V (blue);3. Mass (white);4. Right hand indicator (green);5. Right rear light (brown);6. Left brake light (red);7. Left rear light (black).Note: Pin No. 2 can be used either for a warning fog lamp or a permanent 12V connection.If a LED does not light up, the corresponding wire is defective. If all LEDs do not light up, the mass wire is damaged or all bulbs are defective.Car, Camper1. Insert the tester into the socket of the car.2. Press the yellow button on the side of the tester.3. If the wiring is good, all the LEDs light up. Repeat step 4 as previously described.You can also test the functions of each pin of the socket.1. Switch on the left hand indicator (after switching on the ignition key).2. The corresponding LED must flash with the same frequency. If not, the left hand indicator wiring is defective or broken.3. Repeat steps 1 and 2 for the right hand indicator, rear light, fog light, and stop lights.With a +/- 4m extension cable, you can test the functions from the driver's seat more easily.Note:This product is European style, please confirm before ordering.