Installation of Replacement Trailer Lights on Boat Trailer with Multiple Ground Wires

Published 01/25/2018

Products Featured in This Question

Optronics Combination Trailer Tail Light - Submersible - 8 Function - Incandescent - Driver Side

(1216)

$27.70

Trailer Wiring Junction Box

(820)

$32.29

Peterson Trailer Tail Light - Stop, Turn, Tail - Incandescent - Round - Red Lens - Passenger Side

(1083)

$10.44

LED Combination Tail Light Kit for Trailers under 80" Wide - Submersible - Driver and Passenger

(3202)

$62.85

Question:

Hello, I need to replace the tail lights on the trailer for my jon boat Trailstar trailer. I removed the tail lights and noticed a ground wire from my trailer connected to the ground wire on the light on each light see attached picture. I looked at the connector for the wiring harness on the front of my trailer and noticed it is a 4-way connector, but has three ground wires coming out of it a total of 7 wires ,see other picture. Most of the lights I see on your website have a ground wire with a ring connection that attaches to the studs where the lights are mounted. If I use these types of lights, what do I do with the 2 extra ground wires coming from my trailers 4-way connector that currently connect to the ground wires on my existing tail lights? Also, do you have any recommendations for LED submersible tail lights? Thank you.

asked by: John

Expert Reply:

If a trailer is made of aluminum rather than steel it will sometimes need ground jumper wires on each light since the aluminum frame does not always provide enough conductivity. Steel frame trailers can usually do with just one main ground wire that connects between a clean bare metal spot on the frame and a wiring junction box like # 38656 where all the individual lights' grounds will join it.

Junction boxes can still be used on steel frame trailers, especially when it comes time to install new lights. The box provides both handy connection points and some protection for those connections. From your description it sounds like you could actually have a 5-pole wishbone harness (these have multiple brown running light wires) that could have been installed with those wires acting as grounds. You can refer to the linked article on trailer connectors and wiring to see all connector types in common use.

Some trailer lights will use a wired ground, such as # 271595; others will use the mounting hardware to establish ground; still others like # 431800 use their mounting studs for ground. The light won't care how its gets grounded so long as it does.

Since you're interested in submersible high-efficiency LED lights you might want to just avoid the old wiring altogether and use a complete kit like # TLL9RK or one of the other kits shown on the linked page. We have both incandescent and LED types but LEDs are a great option for upgrading since they do not require periodic replacement, use much less power than standard bulbs and are a lot brighter. Plus, using a complete kit means no guesswork about things like wire gauge.

expert reply by: Adam R