Boat trailer ground connect to tongue or the plug?

[The motor guy]

So recently I've learned you shouldn't have a ground wire connected nearby each light fixture on a boat trailer. This may work fine ona trailer that doesn't go into the water all the time, but it was suggesting to run a ground wire from the lights all the way up to an area on the tongue that does not get dipped in the water. Makes sense because the ground connections that go under water never stay clean enough. My question here is every trailer wiring harness I see always has 3ft of white ground wire that's connected to the tongue. That does not do anything if every light has an individual wire connected to the trailer like I mentioned above. Shouldn't I have all those lights on one ground wire, then connected with a butt connected into that one 3ft long pigtail? Then it relies on the vehicles ground. Or is terminating all the grounds on a clean spot onnthe trailer tongue the better method to eliminate a bad vehicle ground giving you issues?

 

[oilboy123]

I worked on fair amount of boat trailers at work. I retired Sept 2023. Normally the main ground is located near the front under a bolt head, or a fastener. Then a ground at each light location. I used dielectric grease on everything. Trailer connectors included. I don't know if there is a premium trailer harness available. But there should be. They are cheap junk..... It is the only thing that we used....... non tin coated copper.

The EZ Loader trailers all came totally dry of dielectric on everything. Bullet connectors inside the frame.... bone dry. Anything I touched was coated with dielectric. Doing what you mention should work fine. You will just need to find a good way to have all the lights tied to a ground at the front near the tongue. Which is doable. Some of the trailers I worked on had a lot of lights. Not my favorite job to do at the time

Without the white wire connected to the tow vehicle nothing will work. The lights have to be tied back to the tow harness by wire, or frame ground. If using the frame pieces, they all need a good connection to each other.

 

[Wireman1987]

I am no trailer man but i would use heat shrink butt connectors and any grounds made to the trailer chassis would be a heat shrink ring terminal. and whatever means of fastening the ring terminal bolt or screw, i would spray battery terminal coating on it. preferably through-bolting the ring terminal.

 

[SwampSurvivor]

I have a few trailers and I always run a separate ground circuit. Technically, yes, you can get by with grounding the plug to the frame and all of the lights to the frame. But I've had that fail. I like to run a separate ground circuit, then tie it into the plug to the truck and ground that out to the frame as well.

 

[wings&wheels]

I've thought of wiring the light grounds directly to the plug, but have never had a problem but we only trailer 2x per year and fresh water. That said, I do brighten up the various ground contact areas on the trailer, use stainless star washers and slather all connections with dielectric grease.

 

[The motor guy]

I worked on fair amount of boat trailers at work. I retired Sept 2023. Normally the main ground is located near the front under a bolt head, or a fastener. Then a ground at each light location. I used dielectric grease on everything. Trailer connectors included. I don't know if there is a premium trailer harness available. But there should be. They are cheap junk..... It is the only thing that we used....... non tin coated copper.

The EZ Loader trailers all came totally dry of dielectric on everything. Bullet connectors inside the frame.... bone dry. Anything I touched was coated with dielectric. Doing what you mention should work fine. You will just need to find a good way to have all the lights tied to a ground at the front near the tongue. Which is doable. Some of the trailers I worked on had a lot of lights. Not my favorite job to do at the time

Without the white wire connected to the tow vehicle nothing will work. The lights have to be tied back to the tow harness by wire, or frame ground. If using the frame pieces, they all need a good connection to each other.

Thats correct. The wiring harness plug on the trailer side has a white that goes straight to a mounting bolt on the tongue coupler. I dont see what good that does though because all the lights are already grounded to the frame.

 

[The motor guy]

I have a few trailers and I always run a separate ground circuit. Technically, yes, you can get by with grounding the plug to the frame and all of the lights to the frame. But I've had that fail. I like to run a separate ground circuit, then tie it into the plug to the truck and ground that out to the frame as well.

So on a 4 pin wiring harness on the trailer side, it has a white wire that goes to a ground on the tow vehicle, correct? Why not just bypass the ground connection on the trailer tongue and utilize only the vehicle ground which shouldn't have any corrosion issues? (On a southern vehicle)

 

[The motor guy]

I worked on fair amount of boat trailers at work. I retired Sept 2023. Normally the main ground is located near the front under a bolt head, or a fastener. Then a ground at each light location. I used dielectric grease on everything. Trailer connectors included. I don't know if there is a premium trailer harness available. But there should be. They are cheap junk..... It is the only thing that we used....... non tin coated copper.

The EZ Loader trailers all came totally dry of dielectric on everything. Bullet connectors inside the frame.... bone dry. Anything I touched was coated with dielectric. Doing what you mention should work fine. You will just need to find a good way to have all the lights tied to a ground at the front near the tongue. Which is doable. Some of the trailers I worked on had a lot of lights. Not my favorite job to do at the time

Without the white wire connected to the tow vehicle nothing will work. The lights have to be tied back to the tow harness by wire, or frame ground. If using the frame pieces, they all need a good connection to each other.

I just bought a 100ft roll of 16 guage white marine ancor brand tinned wire to run a ground wire up to the tongue i guess. Or maybe ill just connect it directly to the vehicle ground harness and bypass the tongue connection. Sounds like either way is fine. Thats basically what my entire question is here and the reason for my thread. It's just a jet ski trailer, so I'll only have two heat shrink butt connectors for the tail lights in the water for the ground connection atleast

 

[oilboy123]

Yes that will be an easy one vs double axle 30 foot trailers I've worked on. I think the reason they ground each light is redundancy. But that is JMHO.

 

[JHZR2]

So recently I've learned you shouldn't have a ground wire connected nearby each light fixture on a boat trailer. This may work fine ona trailer that doesn't go into the water all the time, but it was suggesting to run a ground wire from the lights all the way up to an area on the tongue that does not get dipped in the water. Makes sense because the ground connections that go under water never stay clean enough. My question here is every trailer wiring harness I see always has 3ft of white ground wire that's connected to the tongue. That does not do anything if every light has an individual wire connected to the trailer like I mentioned above. Shouldn't I have all those lights on one ground wire, then connected with a butt connected into that one 3ft long pigtail? Then it relies on the vehicles ground. Or is terminating all the grounds on a clean spot onnthe trailer tongue the better method to eliminate a bad vehicle ground giving you issues?

If you ran all lights up like that, why wouldn’t you then connect them all to one or two ground points? A secondary ground/bond from the frame to the coupler would be used to improve the grounding performance and keep the potentials everywhere the same. Then one main point I’d assume would go to the same connector or trailer harness on a conductor of suitable ampacity.

 

[The motor guy]

If you ran all lights up like that, why wouldn’t you then connect them all to one or two ground points? A secondary ground/bond from the frame to the coupler would be used to improve the grounding performance and keep the potentials everywhere the same. Then one main point I’d assume would go to the same connector or trailer harness on a conductor of suitable ampacity.

Well the idea is to just connect them to a ground point that doesn't get submerged in salt water. I guess you're right it won't hurt to do both the frame and the ground on the wiring harness. That will also hold the ground wire against the tongue being connected to it vs just dangling around up there by the tongue. My other boat trailer is aluminum, so ground issues aren't as big an issue as eith this galvanized ez loader jet ski trailer. Im not really a big fan of grinding off the galvanized coating either so it can start rusting, but its one of those things I guess.

 

[JHZR2]

Well the idea is to just connect them to a ground point that doesn't get submerged in salt water. I guess you're right it won't hurt to do both the frame and the ground on the wiring harness. That will also hold the ground wire against the tongue being connected to it vs just dangling around up there by the tongue. My other boat trailer is aluminum, so ground issues aren't as big an issue as eith this galvanized ez loader jet ski trailer. Im not really a big fan of grinding off the galvanized coating either so it can start rusting, but its one of those things I guess.

I don’t know best practice for trailer frames. But I’d assume that you’d want the individual lights, the frame itself, and the coupler to all be the same potential, and then that to be consistent with the vehicle. Obviously conduction through the hitch is a path, but this makes the right path.

 

[4wd]

Endless battle in saltwater …

 

[The motor guy]

Endless battle in saltwater …

I had the passenger side tail light quit working halfway thru the drive home then started working again the next time I took the ski out a week later and I didn't even attempt to fix it. I was just like whatever. Every trailer you see has a tail loght that doesn't work. The led lights aren't nearly as problematic as the incandescent lights were. Those lights were just junk to begin with. They all had the same issue. The little tab that makes contact with the light bulb would lose its springiness and they would quit working

 

[The motor guy]

A lot of the issues I think is the poor quality wiring to begin with. It's only 18 guage and after a few years the copper turns black from corrosion. I wonder if I spent $200 on some good tinned marine grade wire if most of these random ghost problems would disappear like a tail light not working then working again the next time you use tbe boat.

 

[4wd]

I had the passenger side tail light quit working halfway thru the drive home then started working again the next time I took the ski out a week later and I didn't even attempt to fix it. I was just like whatever. Every trailer you see has a tail loght that doesn't work. The led lights aren't nearly as problematic as the incandescent lights were. Those lights were just junk to begin with. They all had the same issue. The little tab that makes contact with the light bulb would lose its springiness and they would quit working

Yeah, I see some guys build a portable set that goes in the truck before backing down in the water …

 

[The motor guy]

Yeah, I see some guys build a portable set that goes in the truck before backing down in the water …

I wouldn't be surprised if those quit working too.

 

[Elkins45]

Each of my lights is grounded to the frame with a stainless self-tapping screw. Every couple of years I back them out and hit the frame with sandpaper. By the time that stops working your wiring harness probably needs to be replaced too. I’ve just kind of resigned myself to doing a rewire every few years anyway.

 

[Donald]

Endless battle in saltwater …

Thus why my boat trailer never goes in the water.

 

[Donald]

I do not think the issue is limited to boat trailers. Steel utility trailers can have the same issue.

The only long term solution is a ground wire to each light. The frame can be grounded also. And the ground needs to follow the wiring harness into the two vehicle. Don't count on the trailer hitch ball to provide ground.

Avoid the "blue quick splice wire connectors".

Any connectors that will get submerged should be adhesive lined.

If I was rewiring any areas that get submerged I would try and use marine wire which is tinned copper.

Many disconnect the trailer wiring connector before submerging the trailer. But that may have really been for incandescent bulbs. Most are LED now.