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Your Trailer’s Light System

Trailer lighting ensures that your trailer is legal with the state’s Motor Vehicle department. Safety is paramount. Other drivers will be able to see where your trailer is. A functioning set of trailer lights & brake cables is essential in poor visibility and darkness. It will protect your boat from serious damage and collisions. Do not compromise on the quality of your trailer lights. These lights are essential safety equipment for boating.

How your trailer lights work

Trailer wiring is composed of a plug that connects to the tow vehicle’s lighting circuitry and a matching connector for the trailer. A wiring harness runs the length and includes a variety stop, tail, and turn signal lights.

Multi-function lights can combine up to seven functions in one compact fixture. This includes both reflectors and lighting functions. This makes wiring and mounting lights much easier.

Shining in a Tough, Rough Environment

Due to:

Thermal shock can occur when hot or warm lights are submerged in coldwater. Submerging lights can cause short circuits, corrosion and burnt filaments. Saltwater is particularly susceptible to corrosion.
It can become a corrosive mess if it gets in the connections.
Hours of vibration on the highway can cause damage to incandescent bulbs filaments, causing them to break and become loose.
A drop in voltage due to high current draw from multiple lights from the trailer towing vehicle to the trailer’s taillights.
Covers that protrude from the light source and attract objects like fences, high curbs, or lampposts when they are backing up.

Trailers over 80 Inches Wide

There are two types of trailer lights that the law requires: trailers less then 80 inches wide and trailers larger than 80 inches. Trailers with less than 80 inches in width must have side and rear reflectors, stop lights, turn signals, tail lights, and side marker lights. A license plate light is required. Additional side marker lights or side reflectors may be needed for trailers longer than 80 inches.

To help define the trailer’s perimeter, trailers larger than 80 inches in width will require additional lighting. Three red identification lights must be installed at the rear of the trailer. They are typically sold as a single bar, with the lights placed at the appropriate spacing (similarly to the tops on tractor-trailer trailer rigs and the rears of their trailers). Clearance lights are needed on both sides to indicate the width of the trailer to other drivers. They should be placed as far as possible outboard (usually on the trailer fenders).

Matching existing lights

A quick fix may be all you need if your lights aren’t lighting up. Clean the mounting bolts of your existing lights before you buy a new set. Common problems with lights are caused by improper or “bad” ground. Many lights will ground to the trailer frame electrically through the mounting hardware.

We recommend that you replace your entire trailer lighting system if you are having trouble with your lights. A new light kit and wiring harness is only $25 and can be installed in about an hour. You may find it difficult to run wires through a trailer box section. Before you pull the wires out completely, it is a good idea to pull a messenger. The trailer plug should be removed from the old harness. Tie the end of your new harness to it. Next, carefully remove the old harness from the rear end of the trailer.

Connecting Color-codes & Converters

The Wiring Harness Color and Function Chart shows how basic color-coding works. Paradoxically, the white wire is the ground wire. The trailer hitch acts like a ground. However, the white wire should be connected to both the vehicle ground as well as the trailer frame. The brown wire runs to the taillights. It connects to the clearance and identification light as well as the red lights at the back. The right turn indicator is the green wire, while the left turn indicator is the yellow wire.

Use household “wire nuts” for your trailer. Keep corrosion away from the wiring by connecting your lights to waterproof adhesive-lined butt connections. Make sure to use a high-quality tool such as the Ancor Stainless steel Wire Cutper Crimper.

Some American, Japanese, and European vehicles use different circuits for turning and brake lights. A five-wire-to-four-wire converter is required if your vehicle has amber rear turn indicators or uses a different area for turning and braking. These converters are inexpensive and can be permanently attached to the wiring harness of your tow vehicle.

LEDs or incandescents

LEDs are able to address the shortcomings of traditional trailer lights. They can burn out from vibration or cold water and consume more electricity. The following are some of the LED benefits:

Higher life expectancy: LED lights can last up to 100,000 hours, compared to the 3,000 hour service life of incandescent lamps. Plus, LED lights do not have filaments that break from vibration. This almost guarantees that you won’t need to replace a bulb ever again. The lights can also last the lifetime of your trailer (except when you accidentally back your trailer into a fence ).
LEDs are indestructible to road grime and submersion. LED lights are sealed in a welded lens made of polycarbonate so that there is no chance for the bulb base to corrode or shorten.
No thermal shock: LED lighting generates very little heat, so thermal shock from immersion is not an issue.
Low voltage drop: LED lamps draw only 1/8th of the current as comparable incandescent lights, so the voltage drop is very minimal.
Low profile: LED lights have a very low profile, which means that they are less likely to collide with a protruding light.
The LED lights turn on instantly. Drivers in front of you have an additional half-second to apply their brakes if you come to a halt quickly.

Waterproof lights

Submersible lights allow water to enter the unit when it is submerged. The “Bell-jar principle” creates an air pocket that allows water to enter the socket and bulb. However, water cannot be in direct contact with the bulb. These lights also come with waterproof “capsules” to protect the bulbs from thermal shock and corrosion.

Lights that are waterproof like our Sealed Oval Trailer Light Kit are sealed to ensure no water ingress. All LED lights are permanently sealed.

Harness with split or crossover wire

The majority of trailers use a split Y wiring harness. This cuts at the trailer’s tongue, and runs down each side. This type of harness is included in all of our Trailer Light Kits.

A crossover wiring harness may be used to wire your trailer. It runs from one end of the trailer to the other between the taillights.

Checking your Lights

Always inspect the lights before you tow your boat. To check the lights, you will need to connect the tow vehicle with the trailer. A helper will be needed to operate the brake lights, turn signals and taillights controls. You should inspect the lights more often than once a season. You should inspect every inch of the wiring harnesses and attach any loose sections to your trailer’s frame using wire ties or clamps. Check for any nicks or damage to the wiring. Clean the wire plug at the coupler’s end with 400-grit Sandpaper. Finally, lubricate the contacts with dielectric grease.