You are getting your boat ready for the first trip to the water, and in inspecting all safety features, you discover that your boat trailer lights are not working. Now, how to troubleshoot boat trailer lights would be your next quest. Driving the boat to the boat launch, if you happen to be spotted by the police, you will be given a ticket, the same as if your car's lights were not working. Some officers might be lenient and give you a break, making you show up at the police station within a pre-determined time frame, normally 72 hours, to show that you have fixed the lights. So, why take a chance when it really is not all that hard to troubleshoot faulty boat trailer lights.

The first step in troubleshooting boat trailer lights is to figure out what is wrong. Attach the trailers' electrical harness connector to the matching receptacle on your vehicle, and start your vehicle (so that you do not drain your vehicle's battery). Have someone stand behind the boat trailer as you apply the brakes, and turn each turn signal on, and then the four-way signals. If only one turn signal light, or one brake light is not working, then it is more than likely just the bulb. Pull the faulty boat trailer light out, and take it with you to the store to get a replacement. Install the new bulb then check the boat trailer lights again.

If all is well, be on your way. If the same bulb is not working, test the bulb with a bulb-tester, or multi-meter. If the bulb is good, then the problem is most likely inside the electrical harness. Run a new 2 line wire from the bulb to the vehicle's battery, and connect the right ends to the positive and negative posts of the vehicles battery. If the light turns on, then the wiring harness is most definitely the problem, so your next step would be to either buy a new harness at an electrical supply, boat supply, or general vehicle supply store (Canadian Tire, NAPA, Marine stores, trailer suppliers, etc.), or to buy a used harness from a boa retailer, marina, or anywhere that they sell and repair boats and boat trailers. Repeat this process for all of the boat trailer lights, holding off on buying the harness until you know that that is the problem.

Run the new trailer harness as the old one is, then remove the faulty harness. Connect all of the boat trailer lights to the new harness, then check again to make sure that they all work. If they do, then it's time to head on out to the water! If not, then it is time to check the fuses, as a fuse may have blown while checking the lights, or while installing and testing the new harness. If there is a faulty fuse, replace it with the same rated fuse, then re-test the lights.

If they work, be on your merry way. If they do not work, then the problem could be in the electrical harness that is in your vehicle. To test this, if you have a spare battery, connect a wire from inside each positive and negative posts on the boat trailer harness (black and red, or black and white leads) to the right posts on the battery, or run the wires to the battery in your vehicle (again turn on your vehicle after attaching the wires properly). If the lights work, then the fault is the harness inside your vehicle, and it needs to be replaced, This is usually best left to a garage to replace, in order for the warranty to still be valid.

Happy boating!

Learn more about this author, Marc Phillippe Babineau.
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