Trailer Lights Bite

By Tom Neale, 12/3/2012


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You’re ready to go. The boat stuff is in the boat, the truck stuff is in the truck, everything is tied down, you back up to the trailer and you do stop with the ball right under the coupler and you don’t jam the coupler into your tail light. This is going to be a great day. Until you plug in the trailer lights. Only one or several or maybe none work. Or maybe they all work until you hit the turn switch or the brakes and the trailer lights don’t have a clue. DAMN.

So what do you do? I suspect (I’m only guessing, I have no way of knowing these things) that many just take off for a day of fishing and fun in the sun with the little white lie ready to slide out, “Well, Gee, Officer, I swear it was working when I left.” Which I guarantee he’s heard before. Maybe tried it himself a time or two.

Trailer Light Kit Front View.
Why should we expect them to work? In the first place they’re almost universally cheap. In the second place we dunk them in the water all the time and these things use electricity!! But there are some things you can do to ride herd on them.

The first is to be sure that ground wire screwed or otherwise hooked to the trailer is making a solid contact. Usually the contact is where it gets wet every time it rains and the metal of the wire is different from the metal of the contact which is different from the metal of the trailer. This means corrosion which means bye bye grounding. Sometimes just backing off the screw (if you can) and jiggling it will do the trick. Regularly backing off that screw before it gets corroded and applying a high quality moisture dispersing corrosion block lubricant product will help.

Another thing is to thoroughly spray the bulb base (remove the bulb to do this) and wire contacts in the light with a high quality moisture displacing lubricant when you first get the trailer and periodically thereafter. Also fresh water spray the lights (at least the ones that have been submerged) each time you put the trailer away—especially if you launch in salt water. (You should be spraying down the entire trailer anyway.) Sure, the fresh water may not make it into the bulb cover but this may help. Don’t use high pressure when you do this. It could impair the sealing.

If your light set is designed for immersion (and I wouldn’t want one that wasn’t) then take care about breaking the sealing system if you wish to enter the light/lens casing. Obviously, impairing the seal would normally do far more harm than good. Read the manufacturer’s instructions on this point before you enter the casing.

Trailer Light Kit Rear View showing wire harness.
Also, maintain the connectors. Whenever I see the word “maintain” I think, “Oh no, not another maintenance job.” But it’s not a big deal. All you need to do is to regularly spray the connector holes and connector studs with that good ol’ moisture displacing lubricant. At first you may need to dust them off with a rag (which you should have in your back pocket anyway since all your money is “invested” in the boat and rig). When you leave the trailer you should be sure the connector is left in a protected manner so that it is out of the rain or at least hanging down so that rain water won’t run into the wires. This is easy enough. But even as a connector hangs from the trailer hard rain will often splash mud or sand up and it will cover the contacts on the connector. The receptacle in the truck will also collect dust from the road, even though it’s sealed. Check for grit and take care of it. Maybe just blowing out the female receptacle is all you need to do.

Also be religious about unplugging the trailer lights from the tow vehicle when you’re on the ramp, just before you back the trailer into the water. Electricity under water can ruin the lights quickly and also blow fuses. Do the same thing before you back the trailer in the water to retrieve the boat. I stress to not unplug until you’re on the ramp and ready to launch because the lights are important at the staging area and some trailers (as those with surge brakes) need the DC current to activate a solenoid which prevents the surge brakes from kicking in as you back. That can be a nasty little surprise. If you have surge brakes be sure you understand them thoroughly.

Tom’s Tips About Trailering

There are many special tricks of the trade that are often overlooked but are extremely important. For example:

1. Failure to keep your bearings properly greased could cause the loss of a wheel.

2. Improper loading of the trailer tongue can cause serious issues.

Click Here for More Tips

Carrying along a spare bulb or two for each light doesn’t cost much and can often save the day. Most trailer light bulbs are pretty generic and easy to find. Remember, if the trailer has the light, most jurisdictions are going to require that it work. To change the bulb you’re probably going to have to unscrew the light lens. Usually this simply involves bringing along a screwdriver or appropriate socket wrench. Just take a look, see what you need and keep it (them) in the tow vehicle.

Equally important is to carry a few spare fuses for your tow vehicle and to know where the fuse box is that holds the fuse for those lights. In some vehicles there may be two fuses protecting the light. It’s worth your time to get a mechanic to tell you, if you can’t figure it out yourself, where the fuses are and then to buy some spares. They don’t cost much and are easy to replace. Blown fuses are very common with trailer lighting because of the likelihood of shorts due to the rough usage of the wires and the moisture. Take a look at how skinny those wires are, how thin the insulation is, and consider that they’re wire tied (probably) to the trailer frame, blown by near hurricane force winds and then doused. And if you blow a fuse, odds are that you’ll blow another unless you find and fix the problem, which you might not be able to do at the ramp or on the road, so it’s important to carry more than one. Of course, it isn’t good to keep blowing fuses--the way to go is to find the problem and fix it. But if your lights go out in the dark as you’re driving home, the best temporary solution may be to replace the fuse, if that’s blown.

Are you beginning to see a theme here? I mentioned it at the outset. These things are relatively CHEAP compared to overall boating expenses. Wonder why? Maybe because everybody figures they aren’t going to last long no matter how well you make them. But here’s the best solution.

Replace the entire set, wires and all, every few seasons. They’re not only relatively inexpensive, they’re usually easy to find. And because they’re not very expensive, get the best that you can find. It won’t cost that much more and it’s more than worth the little bit extra you spend. Replacing the set is not a difficult job. You’ll need to get a set that works for your trailer, but this is usually easy enough. Just look at what you have and follow light guides, such as those provided by West Marine. You can use the wires already in place, which you are replacing, to pull through the new wires. If you have wires of extra length in the new set, don’t cut, splice and try to seal them, just neatly and securely bundle them out of the way with wire tie. Avoid sharp turns in the wire. These may crimp the wire, harm the insulation and even cause a break in the wire. Also carefully avoid installing the wires next to a sharp or rough edge on the trailer or in a manner that could cause chafing.

So, enough already. Let’s go fishing.



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