General trailer question

Seems like trailer wiring issue are almost always related to a poor grounding wire. Why are ground wires not run individually back to the wire harness? Seems like grounding to the trailer always rusts and causes poor connection.
I am rewiring a smaller trailer that I bought 1 year ago. It’s a 2014 and i had to brush of rust to get to work. Looks like previous owner had problems with ground also due to multiple holes drilled in trailer for ground connection. Any reason not to run ground wires back to harness to prevent this problem in future?

Thanks for responses in advance.

Wherever I ground to the trailer, I use a Dremel tool and a mini wire brush. Drill a hole for a good size self-tapping screw. Wire brush to bare metal around the hole, and anchor the ground wire. This much is common sense.

Now for the secret sauce. Cover the whole ground screw and terminal loop with Sportsman’s Goop or ShoeGoo. Then no rust will form around or under the ground. These flexible adhesives are tough and stay put and as long as the wire doesn’t get broken, I’ve had no issues with ground. I’ve done a dozen trailer rewire jobs or more this way.

If you are using LED lights as part of your rewire–and you SHOULD absolutely be using LED lights BTW00–than many of them require an individual ground right at the light. They include a short wire and loop. My concern with running a ground wire back to the harness would be too long of a run.

Grouse

You’re absolutely right. Whenever I rewire a trailer, or repair one that’s acting up, I ALWAYS run a dedicated ground wire right back to the bulbs. Even old fashioned incandescent bulbs get much brighter when they have a good ground.

My guess is that the trailer manufacturers save about 25 feet of copper wire by using the frame, so they do it to save money.

S.R.

Some trailer lights don’t even have the wire but make the ground in the mounting of the light.

Steve Root wrote:

You’re absolutely right. Whenever I rewire a trailer or repair one that’s acting up, I ALWAYS run a dedicated ground wire right back to the bulbs. Even old fashioned incandescent bulbs get much brighter when they have a good ground.

Have you ever had any problems with LED lights not liking the resistance caused by DC current running through that length of ground, Root?

It’s a good idea, but just to throw out there that I’ve found LEDs very sensitive to resistance and unlike the old school incan lights, an LED either works or it doesn’t. They won’t just get dim.

Far and away the most common issues I’ve had to fix with trailer lights were:

1. People using those POS “quick crimp” pinch on splices. If these POS things come with your trailer light kit, THROW THEM AWAY. Total garbage and use of them will absolutely be guaranteed problems down the road.

2. Bad splices using non-waterproof crimp connectors. Either shrink warp or use the waterproof splices.

3. Failure to protect wire anyplace it passes through metal. Use a rubber grommet or loom wherever a wire passes through the frame. Grinding holes smooth is good, but over time wire insulation rubbing against metal WILL fail.

Grouse

Jay, with my trailer I used a piece of #14 THHN wire for the dedicated ground. Absolutely no problems at all; the LEDS work every time and are very bright. Light Emitting Diodes need a minimum voltage to start conducting (and emitting light). Any resistance anywhere in the circuit will cause a voltage drop, and as you said the LEDs can just quit. Mechanical connections are the first prime suspects. Splices, crimp connectors, two pieces of rusty crusty trailer metal bolted together, that sort of thing. I eliminated all splices I possibly could, I solder and weather proof all connections, and again I run a dedicated ground to every light.

S.R.

Steve Root wrote:

Whenever I rewire a trailer, or repair one that’s acting up, I ALWAYS run a dedicated ground wire right back to the bulbs.

Yup. This.
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