naclh2oDave

The problem is that when the headlights on the truck are on and I hit the brake the lights on the trailer all go off. By themselves they work, the brake lights work, the headlights work, the blinkers work. The blinkers and brake work together, the blinkers and headlights work together but the headlights and brake, not so much. Has anyone here ever had this issue?

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countryjwh

i do not know much about lights at all, but every time i have a question they tell me to check my ground. just a thought. hopefully tuna man will chime in, he has helped me in the past.

Tuna Man

Here I am....

First...is this something that just cropped up as everything worked correctly to begin with?... meaning not a new instillation.

How is the trailer wired to the vehicle? Factory vehicle harness or aftermarket.

Without the trailer does EVERYTHING work correctly on the vehicle?

Have you tried hooking up the trailer to another vehicle to see if the same results are present?

When the brake lights go out on the trailer do the brake lights on the vehicle go out also?

Answer these and we'll move on to a test light. It may be from the vehicle and not the trailer.

Do you have a test light? If not go beg, borrow, <STRIKE>steal</STRIKE>, or buy one. Other then having the correct tool needed to work on a boat/trailer a test light is more useful then any other single tool. They don't cost much, but I'd get a good one vs a cheap POS. Also very useful around the house on a vehicle, lawn mower most anything that is powered with up to about 14 volts. I keep one at home and I take the other when I have my boat/5th wheel, or any trailer on the road. And have had to use it on several occasions.

naclh2oDave

I have swapped out brand newlights with consistent results. I also went through and disconnected other lights that were not working. It should be noted that with the truck plugged in AND running the voltage drops down to about 5 volts. Also, some of the wires throughout the circuit are black on the inside. The discoloration goes away when sanded.

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Tuna Man

Your wiring harness by virtue of the BLACK wires is a indication that there was/is a short in the harness, and they are toasted. Hate to tell you but you but what I would do is rewire the trailer. Not a hard job or expensive but time consuming for the novice.

You are looking at a what three or four wire system to the back of the trailer. Four rolls of new wire about $8.00 to $12.00. Most likely you have had more aggravation then that much already:banghead

DreamWeaver21

Mine has done that but usually it is just one side. Running lights work but when I hit the brake it goes out. Academy and U-haul sell little light testers that you can plug into the truck and eliminate that as a problem or if you have access to another trailer that is known to be good then try it just to eliminate the truck. It is probably not the truck. If the lights have a seperate ground wire you can try taking that off and cleaning it up. If they ground through the bracket you are pretty well stuck. You will probably end up re wiring the trailer either way.

X-Shark

Not really. It's more of a indication that water has weeped inside the insulation. It's pretty common to turn green and then Black.



This is due to the use of Scotchlocks that most all manufactures use.









That Black color creates a high resistance in the wiring.



There are better was to wire a trailer so that you will not have problems.

Tuna Man

Those are a piece of crap to say the least. Not bad to use IF not in water.

If you think that the black on the wire (could tell if looking at it)is water relatedas you say then a re-do all connections might be in order first.

Also...Best to disconnect the trailer harness when launching and recovering the boat.

If you think it might be a water problem then I would pull apart every connection, clean wire and re-connect without connectors (just wrap wires) for a test. Problem corrected then use good connectors and repair the connections. If that doesn't solve the problem I wouldn't waste my time and headache over $12.00 and some time...I'd rewire. By the time all this is (whole post) typed read and responded to, I could of had the trailer re wired:banghead:banghead:banghead:banghead

Tuna Man

Here are some ideas for connections. I had to make the extension as I have a jon boat and the trailer tongue is not long enough, and turning sharp the corner of the boat \will crush the taillight on my Yukon:banghead so I made a 2' hitch extension as opposed to extending the trailer.



A.. 4 pin with ground female

B.. 7 pin female to 3 pin male with ground

C.. 7 pin

D.. 3 pin with ground female

E.. 3 pin with ground male

Now everything I have trailer wise is 3 pin female with ground.

naclh2oDave

Thanks for all the help and input guys. I got started early and retapped all the grounds, then I went through and replaced everything with a bulb with new LEDs. Everything is working properly as of now. There was alot of corrosion on almost every ground. They all have new ends and were sprayed with corrosion inhibitor. Thanks again, the wealth of information shared here is priceless. I appreciate it.

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