Your trailer carries your boat, tractor, boxes, or other objects to where they need to be. These objects are often too large, too heavy, or too numerous for you to carry without your trailer, which is why you need it to be in working condition. While this includes having full tires, a stable frame, and adequate tie-down strap, it also includes making sure that the electrical system is up and working. If you start experiencing trailer light wiring problems or worse, brake problems, you'll need to get those fixed as soon as possible. There are many electrical problems that you can fix without going to a professional. If you're not sure, however, make sure to refer to a professional to avoid future problems.
Typical Wiring Problems
While there are many problems that should be left to professional electricians, there are a few that are more common and easier to fix. To help you figure out your electrical problems easier, we've compiled a list of common electrical problems and their potential solutions.
One function of the trailer light system doesn't work, like the brake lights or left turn signal
The harness wires aren't connected, a set of connectors isn't making a strong connection, a fuse blew, the brake wire isn't connected, there's an insufficient ground
None of the light functions work
The 12V power wire isn't linked to the car's battery, the harness has a factory tow package and the vehicle doesn't, there's a blown or missing relay fuse, the harness has a poor connection to the ground or there was a harness overload
The lights worked at first but have stopped over time
There's a loose or weak ground connection, the harness experienced an overload because of an excessive draw or there's a short in the wiring
Switching on one turn signal causes both sides of the trailer to turn on
The brake wire on the harness isn't grounded, or there's an insufficient ground
Turning on the vehicle's headlights causes the trailer lights to stop functioning
There's an adequate ground on the truck or trailer side or an overloaded harness because of too many lights
One or more of the trailer lights remain on, even with the ignition turned off
Improper connection to a truck wire exists, there's an insufficient ground or the trailer has LED lights powered by the 4-way plug
The harness functions until you connect the trailer
There's an insufficient ground or a harness overload when the trailer connects to the vehicle
The trailer's reverse lights aren't working
The fifth wire isn't attached to the reverse circuit on the car, or there's an insufficient ground
Avoid rewiring the entire system until you've checked all of the possibilities. If you're not confident in your ability to fix your electrical problems, consult a professional. To check your electrical system thoroughly, check the grounds, inspect the terminals, check the fuses, determine if the issue is with the tow vehicle wiring or trailer wiring, and when in doubt, always mind the ground wires.