Changing and Fixing Trailer Lights

Properly working trailer lights bulbs is crucial to maintaining road safety. If both bulbs are not functioning or even one is burned out, motorists behind you may not be aware when you are slowing down or planning to turn. Checking your trailer’s light bulbs and replacing them when necessary is an important part of owning a trailer. Best of all, it’s a quick and inexpensive project you can do yourself, even if you’re not very handy.

**Changing Trailer Lights Guidelines**

1.) Test the electric circuit in your trailer with a trailer light circuit tester, available at many automotive supply stores. It will tell you if the dead bulb is actually a dead bulb or if the electrical current isn’t reaching it. Follow the circuit tester’s instructions for usage.

2.) Unplug the trailer power plug from your vehicle.

3.) Remove the lens cover over the dead bulb with a screwdriver.

4.) Remove the dead bulb and take it to an auto parts retailer, where you can match it up with a suitable replacement.

5.) Insert the new bulb in its socket.

6.) Replace the lens cover and fasten it with screws.

7.) Plug the trailer’s power plug back into your vehicle and test the brakes and turn signals.

**Fixing Trailer Lights Guidelines**

1.) Inspect the trailer plug connector on the vehicle side. Probe each connector pin with a test light and make sure each system has the power it needs. Have an assistant turn the lights on and off, switch the turn signals left to right, and apply the brakes. Make sure each connector plug works as it should. Repair any system as needed. Pay particular attention to the ground connection and make sure it is good.

2.) Install the connector plug. Remove each lens cover from the lights. Remove the bulbs. Visually inspect the sockets for rust and probe each light socket with a test light. If the test light illuminates, the bulbs are the problem. If not, the wiring or wire splices are the problem.

3.) Cut out the old wire splices where the lights are spliced into the harness. Test the wire with a test light. If the light glows, the splice connector that has just been cut out was the problem. If the light does not glow, the wire leading from the trailer connector to the light is defective and must be repaired or replaced. Often it is best to run a new wire. Test each light the same way.

4.) Replace the light assembly if it is more than five years old. Carefully inspect the light back plate. Many lights ground through the trailer frame. Exposure to the elements shortens the life of trailer light sockets and the ground terminals, especially boat trailer lights. Rust and corrosion shorten the life of the back plates, often eroding the inside of the bulb connector. New lights are often the most economical way to go.

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