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Author Topic:   Trailer Lamp Replacements, Re-wiring
pvonk posted 07-22-2013 06:05 PM ET (US)   Profile for pvonk   Send Email to pvonk  
I've replaced some [incandescent] lamps (on my Karavan trailer original to my 2005 Montauk with) with LED lamps over the past years, and this time I'm replacing the bar light (rear in the middle, under boat engine). First problem encountered was the replacement bar from Karavan has two wires coming out (actually more, but some are then joined), and the original bar has only one! Karavan told me to attach the extra white wire to the right taillight, which is where the power wire also attaches to. So I began with the taillight. (Before doing anything, I did power up the system and did have two lights on the bar that are out. All other lights on the whole trailer are good.)

Pulled wiring from the frame behind the taillight to get to the connector plugs to see how things were set up. Didn't unplug any wires. Next I discover all lights except for the two side lights near the bow are out. After much work and frustration, I can't get what was working before to work again.

So I'm now looking to have someone repair the electrical, but I can't find any business near me that does it. I may have to continue myself.

I'm now wondering, can I put a new harness outside the trailer frame and not inside it, which is a pain? I figure it would be much easier to put the wires outside and use duck tape or something like that to attach wire to frame. Would this pass state inspection?

Whalrman posted 07-23-2013 08:10 PM ET (US)     Profile for Whalrman  Send Email to Whalrman     
Probably won't pass inspection that way!. Also with the wires/harness inside the frame rails offer protection to the wires from being hit and shorting out the system. Look further here on Jimh's site as I think there is a section on trailers and lights that would help. Make sure that all the ground connections to the trailer are good. You may have pulled wires loose from their connections that were shady at best and add corrosion to the mix and poof no lights.
jimh posted 07-23-2013 08:48 PM ET (US)     Profile for jimh  Send Email to jimh     
Trailer lamps are often wired with the trailer frame as the negative return circuit.

I would not use duct tape to retain wiring.

If re-wiring, consider running a ground wire to each lamp instead of using the chassis as a part of the circuit.

For help with color codes used in trailer wiring, see

Trailer wiring is very simple. There are three circuits

--running lights

--right turn/brake light

--left turn/brake light

Usually there are several lamps wired to the running light circuit. The right and left turn lamps are run on their own circuits. The most common problem is a poor ground connection between the trailer and the tow vehicle.

L H G posted 07-24-2013 01:43 AM ET (US)     Profile for L H G    
With five trailers, all with ALL lights working perfectly, salt and freshwater use, I have experience with trailer wiring.

First of all, use DRY LAUNCH products exclusively. You can order them directly from the manufacturer and they WORK PERFECTLY for years and years. They are completely waterproof. No, they are not LED, but so what? No need to unplug them before launching. One excellent design on the tailights is that the wire connections are inside the fixture, and never get wet. They do not have pigtails to be spliced on to the trailer wiring. All of this means, of course, that your wires are sound and your connections are good. Their marker lights and light bar are also completely waterproof and work, and work and work.

Be sure the white lead coming off the trailer plug is securely fastened to the trailer frame, via bolt or screw and ring terminal. This will guarantee that your trailer frame works as the ground.

Regarding the light bar, the built in ground (via it's attachingment screws), may not function. A separate short ground wire to the trailer frame may fix the problem.

Avoid conventional crimped butt connectors, heat shrink or not. They always fail, sooner in salt water immersion than fresh water. With Dry Launch tail lights, there are no such splices, as the wires from the plug go all the way into the tail light for connection - no splices needed.

But if you must make a splice, such as for markser lights, try conventional plastic wirenuts, of the correct size. Once twisited on, fill the "cup" of the wirenut with Boat Life or silicone caulking and put a small wiretie around the wires coming out of the nut (preventing Pull on the wires). Guaranteed PERMANANT connection that will never fail, no matter how many times it goes in salt water.

Be sure all nuts and bolts in the light fixtures, and the brackets that hold them, are SS. This is the only upgrade I have done with the Dry Launch products, and will guarantee a good ground.

jimh posted 07-24-2013 08:49 AM ET (US)     Profile for jimh  Send Email to jimh     
The original poster has already changed all of his trailering lighting to LED lamps from incandescant lamps, so he may not want to change back. In case he does want to change everything back to Dry Launch lamps, here is a good link to information about them:

Dry Launch Trailer Lamps

andygere posted 07-24-2013 01:23 PM ET (US)     Profile for andygere  Send Email to andygere     
Pulling new wire is a good idea, and one way to ensure that their are no hidden splices. Connect the end of your new wire to the end of your old wire, and pull the new wire through the frame using the old wire as a pull string.

The Dry Launch system sounds good, and the concept of a homerun wire from lamp to trailer tongue makes a lot of sense. I have had excellent success using the Anchor brand waterproof butt splice connectors to connect trailer wiring, and have not had any failures. You do have to be sure to use the correct size connectors, and you do need to use a heat gun on the low setting to slowly shrink the connector and melt the integral hot melt glue. I like to reinforce the connection with waterproof adhesive-lined heat shrink tubing over the top of each splice, though I've had many connections without this extra step hold up just fine.

dfmcintyre posted 07-24-2013 08:14 PM ET (US)     Profile for dfmcintyre  Send Email to dfmcintyre     
I had an neighbor use runs of black plastic 1/2-inch ID water tubing, complete with fittings that he attached to the frame. Thought it was overkill, but looking back on the project, it may have eliminated a lot of headaches...


kwik_wurk posted 07-24-2013 08:37 PM ET (US)     Profile for kwik_wurk  Send Email to kwik_wurk     
I know it looks tacky, but I run my wiring on the exterior, with zip ties. As part of my road travel kit I carry a spare light (left or right), and some wire. I can make an emergency repair in 5 minutes. -- But my trips are typically 150 - 350 miles one way for an extended weekend.

But I do run ground wires, and do have sealed lights. However the splices are exposed. (I used liquid tape on the interior of the heat shrink tubing, and I put two more overlapping layers of liquid tape and heat shrink.)

jimh posted 07-24-2013 09:45 PM ET (US)     Profile for jimh  Send Email to jimh     
I think the risk of water intrusion into electrical connections is perhaps overstated. These connections are not immersed very deeply into the water, so there is not a lot of water pressure. Any properly made splice or connection ought to be able to withstand the exposure to water immersion of only 3-feet at most. Of course, poorly made and poorly sealed connections will be found by water, eventually.

The worst feature of trailer wiring that I see are those in-line pinch connectors that make a splice into a wire. They are typically used for the clearance lamps on the fender. It would be much better to avoid piercing the wire insulation and exposing it to water intrusion, and, instead, to run a separate wire to the clearance lamps, joining them into the running light circuit with a proper splice that is waterproof.

jimh posted 07-25-2013 11:14 AM ET (US)     Profile for jimh  Send Email to jimh     
I disagree with the recommendation to avoid using heat-shrink sealed butt-connectors. When properly installed these are very serviceable in this application. The best advice is to avoid splices, period.
pvonk posted 07-25-2013 04:15 PM ET (US)     Profile for pvonk  Send Email to pvonk     
Thanks to everyone. I got the system to work.

It was the talk in your posts of ground wires that got me to focus on these. When I loosened the right taillight from the frame and after finding the lights not working, I screwed the light back on, finding the lights still not working even though I had everything back the way it was originally (and working).

The back of the taillight has two white wires (one from inside the light box, and one coming from within the trailer frame) with a [gizmo] on each that fits on the screws. I used steel wool to clean the [gizmo] (I don't know what these are actually called) and the frame around the hole that the screws are screwed into and the [gizmo] connect with. And that did it.

jimh posted 07-25-2013 04:21 PM ET (US)     Profile for jimh  Send Email to jimh     
I am not sure what the [gizmo] might be, but often a star washer is used with electrical connections to grounds. The star washer has small points that will pierce though any surface oxidation of the adjoining metal surfaces, and that ensures a good electrical connection. Here is an image of a star washer:


Is that the [gizmo] you mentioned?

jimh posted 07-25-2013 04:24 PM ET (US)     Profile for jimh  Send Email to jimh     
In low-voltage circuits like a 12-Volt DC circuit, the flow of current can be stopped by a very thin layer of insulating material. It only takes a bit of surface oxidation to stop electrical current flow if the circuit voltage is very low.
jimh posted 07-26-2013 11:02 AM ET (US)     Profile for jimh  Send Email to jimh     
Re-reading your description, perhaps the wiring device you called a [gizmo] is just a ring terminal.
Chuck Tribolet posted 07-26-2013 01:22 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
Several years ago, I rewired my Shoreland'r trailer. I used
all 16 gauge Ancor marine-grade wire. I ran a four-foot
cable with flat-four connectors on each from the hitch up
into the winch stand. From there, separate wires, including
a ground, go to each light. All connections are soldered
and sealed with Ancor hot-melt glue-lined heat-shrink tubing.

This has been dead reliable.

I will do the same thing shortly to my new Aluminum trailer
which should show up next week.


fno posted 07-26-2013 11:00 PM ET (US)     Profile for fno  Send Email to fno     
I am in the same camp as Chuck. Soldering is more time consuming and takes more skill that crimp connectors for sure but are 100 times more reliable. The trouble with solder is when the wire is old and corroded. Solder will not stick to it. That being said, if I am wiring new, solder joints, heat shrink with glue inside, and liquid tape are the way to go.

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