• Most common problem is grounding. Most of the grounding is done via frame of the trailer. Two areas needed to be checked 1) where a ground wire is contacted to the metal frame of trailer with a metal screw. Make sure there is no rust or paint and insure metal to metal contact. 2) Where trailer ground is connected to vehicle ground. Makes sure connection to the vehicle is sound.
• Check the fuse. Most of trucks have separate fuses for trailer lights, some even have separate fuse for Left and Right.
More or likely one of pin of the 4 pin connector (or 7 pin) is compromised. Make sure there is no dirt or rust at the contact. Insure a metal to metal contact between vehicle and the trailer connectors.
Not like incandescent lights, LED lights are polarity sensitive; works only one way and + - is not interchangeable. Normally, ground wire is white but not all manufacturers follow that. If one connection is not working, flip it and it will work.
Before making the connection to a vehicle:
1. Test the lights before installation by applying DC 12V (such as from automotive battery).
Verify all the light works, be sure for a correct polarity for LED lightings.
2. Verify vehicle side connector (4 pin or 7 pin) is working properly.
One way to test is either using volt meter or test bulb.
i.e.) turn on the tail light and test between Ground and Tail light pin.
3. After confirming vehicle side connector and the lights by themselves, wire the lights to the trailer and plug in the trailer side connector to vehicle side, if lights not working still, it’s either because of faulty trailer side connector or trailer wires.
Makes sure connectors are clean and there is no bare wire or damaged wire.
LED turn lights require special flasher. The old flasher relies on lots of current to pass through the flasher to work properly. Since LED lights use far less current than incandescent lights, the flasher thinks the bulb is gone bad, so it flashes rapidly.
There are two types of design, independent bulb and common bulb system. If you have separate bulb for the brake light (Stop) and turn lights, then you have an independent system. If you have an independent system, you will need a converter to convert the independent system to a common system in order to use trailer lights.
Yes. Even with submersible trailer lights, there are wire connections that are not water proof, such as wire nuts. It is always prudent to unplug the trailer light as being submerged.
TIP: Double check the ground and always clean out the dirt/rust off from the connectors and make sure there is no pinched wire!!
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