Boat trailer lights Guru needed

G

gcs

Well-known member
The one time I care if the lights work....

Ok, replaced rear rotted out light units, connected yellow to yellow, green to green, brown to brown, and good ground from vehicle to trailer, or so it seems...

With vehicle lights OFF, turn signals work, brake lights work, all is well in the world.

With vehicle lights ON, running lights dim, both blinkers work together like 4 way flashers, apply brakes, everything shuts off.

Bulbs are in correct orientation,

Any ideas? I don't have enough hair left to pull out. :)

Thanks.
 
George, Most trailer light problems stem from poor ground. Don't trust the frame to be a good connector. Run another wire, white if you have it , to the white wire on the plug to each light mount and see if it gets better. I think you are grounding one circuit through the others and making them dim and @$&%!&&*^ed up. Give 'er a try. I do that on every trailer I wire as a precauition.
 
Tom, if I read you correctly, splice a new white ground wire into the white wire of the plug and run it to each light, and then connect that new ground to the frame of the trailer at the light units mounting bolts. Does that sound right?

I noticed when I connected the existing white ground to a bolt on the frame, I got a spark, never noticed that before on other trailers, but I wasn't exactly diligent on making sure the lights always worked, so might have missed it. ?
 
I'd just mount a pair of hand held spot lights on the hood, splice them together, and plug them into the cigarette lighter so you don't have to turn on the cars lights. Problem solved!!!
 
George,

Tom is correct. The symptoms you describe are attributed to a faulty ground. If you are using the trailer frame, then there will be multiple points for failure.

(A) vehicle frame to hitch ball
(B) hitch ball to trailer coupler
(C) trailer coupler to trailer tongue
(D) trailer tongue to trailer frame
(E) trailer frame to trailer light mounting stud

(F) if lights are mounted on uprights you also have a connection at that point


By using the WHITE GROUND WIRE found on the four prong trailer plug, you can eliminate all the above failure prone connection points.

On the tow vehicle side of the plug the white wire needs to be grounded to the vehicle frame. On the trailer side you should run a wire from each mounting stud (one for each light), thru the frame and tongue and connect these all to the white wire provided on the four prong plug. Note side marker light typically ground thru one stud or screw only so be sure to use the one with the brass strip on it. Also connect the white wire to the trailer frame as a back up for the grounding system.

BTW Most trailer come with the white wire connected to the tongue of the trailer. This works while everything is fresh and new but soon starts to give problems of the type you are experiencing.

Also note that if you are using LED type lights these usually don't ground thru the mounting stud but already have a third wire for the white ground wire to be connected to.
 
Dave, Thanks for clearing that up, I had to run and just got back. Boat trailers are hard on lights but nothing like snowmobile trailers. I would guess salt water boaters have just as bad. I have made the $$ switch to LEDs and am very happy with them, but am a little more careful backing up or towing down some bad (good) roads ;-).
 
Thanks for the responses, I'll run separate grounds to each light and hopefully that will solve the problem.
The only thing I don't get, is that the trailer lights work as designed as long as the tow vehicle lights are off. So daytime trailering wouldn't show a problem, but with the headlights on..... , just weird, lol
I'll get on it tomorrow and see if the mystery is solved.
 
George,

Take a voltmeter and read the connector on your vehicle with the headlights off and then with them on, see if there is a difference. As Jim said they may have the wires reversed. Here is a web site that may help you sort it out. At least it will tell you what you should see on each wire using the voltmeter. If you don't have a meter a 12V test light will do.
http://www.etrailer.com/faq_wiring.aspx
 
I'll vouch for what Tom describes above. I got so fed up with all the trailer light problems I had over the years I finally spent some bucks and made the switch to LED's and I did exactly what Tom and Dave said above. After doing so, I have not had a trailer light problem since.

One source of frustration eliminated. LED's all around cost me about $60 I believe.

Mark W
 
jeeze guys this last winter the salt on ever thing was bad i bought a can of silicone spray and sprayed on everything to stop from rusting the nite before a hunting trip came out hooked up no lights ????what the ....they worked last nite .....

well this product i used was very good i geuss and i sprayed it on the ball for lube and protection and the wiring plug in on the bumper..anyway i figured out what it was and rubbed it off they have worked ever since,i had to think tho at minus 10 what the heck chnged from last time the trailer was working the silicone spray was the only thing...

trailer lights are a pain i prety near every year replace them from being in the salt fromt he roads and being in the salt water..

20 to 30 bucks for lights every year...its a must...
 
UPDATE... You guys are all right, no matter what other people say. lol

First of all, the wires on the new lights were correct, the Chinaman who wired it must not have been color blind.
I ran a dedicated ground wire to the lights,connected to the frame of the trailer, and to the plug ground wire.
WOW, Everything works exactly as they should, nice and bright, and no weirdness. Actually, I never had a trailer that everything worked right, all at the same time.

Dave, you have to add a new potential problem area to your long list, and that is tip up trailers, there just doesn't seem to be enough meat on the rusty pivot to convey a solid ground.

Anyway, thanks for your help, now I got to fix the little trailer, no problamo now.
 
Most trailer lights are a pain in the wazoo. I usually check the ground setup when mine give trouble. I put a circle fitting on the ground wire, drill a small hole in the coupler mount and screw the wire to the trailer. WD 40 the heck out of it from time to time to keep it drier. The companies that sell the wiring/light setups don't want them to last forever.

Also I always unplug my lights before I immerse them, as it saves bulbs.

Best,
Harry
 
In my experience all trailer light problems are always the ground, and usually the ground between the vehicle and trailer. All of the weird symptoms of weak lights, strange flashing, turn signals working and brake lights not, all indicate a stolen ground. That is trying to find a ground through the other circuit with a common bulb.

I too have LEDs on my new trailer and love them. I plan on switching out the fixtures on the other trailer when I have my first problems with the existing lights (which are only 2 years old).
 
I went LED on one of my trailers last season, I grounded the white wire at the hitch after pulling all new wires through the frame.so far zero problems.

Brad is right, the ground is 99% of all light problems, I will go all LED when my jet boat trailer needs fixing.

Fred
 
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