#4 pin trailer wiring diagram how to

We reviewed that the trailer frame is ground, so go ahead and connect the negative clip from your test light to the trailer frame. A visual inspection is good, but a multimeter or test light is the best way to confirm. This will protect the light from further damage caused by excessive power. Once that amp rating is exceeded, the wire inside the fuse will break, causing an instant disconnection to the light. A fuse is a plug with a wire with a certain amp rating. Step 1: visually inspect the fuse to see if it is blown. Whether you have an inline fuse or a fuse box, this process is the same to determine if the fuse is bad. The next step is to check if you have blown a fuse. A fuse box usually has a fuse cover that lets you know which fuse goes to where. This fuse panel will house your fuses, including your running lights. The inline fuse type should be waterproof, but sometimes water does get in them and can cause a short, creating a blown fuse.Īnother setup besides the inline fuse is a fuse box or fuse panel. This type of fuse will have a set amp reading that will blow a fuse for safety if there is a short that would cause damage to the lights. Your trailer lights may have a separate fuse, which can be an inline fuse. FuseĪnother common cause of your trailer running lights not working is a blown fuse.

#4 pin trailer wiring diagram how to

Being this is a ground wire you don’t need to be as worried about waterproofing the wire itself.įor more in-depth testing on this, visit my post on how to check your trailer ground wiring. Get to shiny metal for a good connection.Īlso, reconnect with a wire nut if you see any damage or break in the wire. If you see corrosion, unscrew the wire from the frame and clean it with sandpaper or a wire brush. Check it for any corrosion or rodent damage. Visually inspect the white wire that goes from your running lights. Seeing that the rest of the lights are working, your trailer is getting some ground, just not at the running lights. If only your running lights are not working, the common cause is usually the ground wire going from that trailer light to the frame. This makes it easy for a light to be connected to a nearby piece of the trailer frame to get ground. By doing this, the entire trailer frame acts as ground. Your ground wire is connected to various parts of your trailer framing. All trailer lights and pins use this one connection as their ground source. When you look at a 4 pin wiring diagram, you will see 3 pins for the lights and 1 pin for the ground. Any corrosion separating the wire from the frame will cause the ground not to work, as well as your trailer lights.

This ground wire is exposed to the elements, is known to corrode, and does not have a good metal-to-metal connection. The ground wire is the white wire usually attached to the trailer frame by a screw. The most common issue for trailer wiring issues is the ground wire. We will focus on the special characteristics of this connector and determine why the running lights are not working.

Unlike a 7 pin connector, the 4 pin connector has only 3 wires and one ground. This post will review the common issues and the solution to fix this problem, including: Even with just a few wires, sometimes things go wrong, and you may not have things work, such as your running lights. A 4 pin connector is used in many applications, including a utility trailer or boat trailer.