Diagnosing A Faulty Trailer Electrical System

3 May 2017
 Categories: Automotive, Blog

To legally drive your utility trailer, it is necessary to have taillights in order to communicate with motorists driving behind you. This requires an electrical system that is run through the utility trailer. When the wiring becomes defective, it will be necessary to have the wiring repaired in order to drive safely on the road. While some problems are easy to repair, others can be difficult to diagnose.

Early Tests

Determining whether your lighting is working at all is very easy. Simply connect the harness and then ask a friend to check whether the lights are turned off or are dim. If the lights aren't fully illuminating, disconnect the harness and plug a tester into the outlet on your vehicle that you plugged the harness into. The tester will tell you if the problem is actually with your vehicle. The most common problems that may prevent the utility trailer lighting from working properly include:

  • A bad flasher
  • A blown fuse
  • A burned-out light

Inspect the connector and make sure that there are no wires that are broken. If there are any broken wires, they will need to be replaced.

Checking The Ground

It is important to understand that grounding is an essential part of a trailer electrical system regardless of the type of trailer that you use. If there is a bad or missing trailer ground, this is one of the most common reasons for why the trailer electrical system does not work or why one component of the electrical system does not work. The pin on the truck socket and the pin on the trailer plug are dedicated to serving as the trailer's ground. This may need to be replaced.

When Only One Component Is Malfunctioning

In some cases, the trailer lights might work, but some of the functions are not working properly. For instance, the brake, right turn, left turn or tail may not be working. This may be a problem with the harness wires not being connected properly. Or, there might be a blown fuse or relay. Some trailers might have separate turn signal and brake light wires, with the brake light wire not being connected.

A Note On Wire Colors

Do not assume that the wiring color codes are correct. Mechanics and previous owners of your trailer may have used different colored wires. Instead, focus on the function of the trailer plug and the pin location. Be aware of the orientation of the plug when matching a pin to a function.