7 pin trailer tester, 12V trailer lights tester cable wiring circuit diagnostic tool. The tester is designed to European standards and is used for car, caravan, RV, trailer, and carrier applications. Specifications: Material: ABS and copper Voltage: 12V DC Contents: 1 x 7 pin tester, 1 x 7 pin to 13 pin adapter, 1 x 13 pin to 7 pin adapter Color: Black Item Type: Diagnostic Tool Item Name: Trailer Tester Battery Type: 9V (battery not included) How to test the connection of a trailer (including caravan, bike rack, or other commercial vehicle): 1. Connect the tester to the plug or socket. 2. Press the yellow button on the side of the tester. 3. If the wiring is correct, all LEDs will illuminate. Function of each light (according to ISO 1724): Left indicator (yellow) Fog light or 12V (blue) Ground (white) Right indicator (green) Right rear light (brown) Left brake light (red) Left rear light (black) Note: Pin #2 can be used for either a warning fog light or a permanent 12V connection. If an LED does not light up, the corresponding wire is faulty. If no LEDs illuminate, the ground wire may be damaged or all bulbs could be defective.