Convert your trailer lights to LEDs and add individual grounds to eliminate the two most common causes of light failures.
Run the new harness and the extra ground wire through the split loom tubing. The loom protects the harness from rub-through and shorting inside the trailer frame.
Strip the ends of the new harness wires and secure them to the mason's line. Then wrap the entire connection with electrical tape to make sure it doesn't come apart during the pull.
Connect the lighting and ground wires to each light with a crimp connector and heat-shrinkable tubing. Then splice all the individual ground wires to the harness connector ground wire.
When it comes to trailer lighting, nothing causes more trouble than burned-out bulbs and corroded ground connections at the frame. Rubbing (and shorting) connections come in a close second. If you want to get rid of those problems forever, switch over to LED lights and add an individual ground wire to each light. The entire project takes just a few hours.
The trailer light kit we used (Blazer International No. 127680; about $54 from amazon.com) comes with a new harness. At an auto parts store, buy a spool of 16-gauge wire for the individual ground wires. Then buy crimp connectors and a few packages of split loom wiring harness protectors (Curt Manufacturing No. I-1824-25; 25-in. length; from amazon.com).
Disconnect the old trailer harness wires at each light and attach mason’s line. Then pull each line back toward the trailer tongue. Connect this “fishing line” to the new harness and loom (Photo 1). Next, pull the new harness through the frame (Photo 2). Finish off the installation with crimp connectors and heat-shrinkable tubing (Photo 3).
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.