Trailer Lights not Working; Am I an idiot? Please help.

[jrcarte78]

O.K. here's my situation. My trailer's tail(running) lights will not come on. My brake lights work fine. I've got one bulb out in the rear(starboard side) that I will replace tonight. But, the other bulbs are fine and will still not work i.e. the 2 lights in front of the fenders, the three underneath the boat, and the tail light in the port rear fender. The starboard rear tail light is the one that is out and I'll replace the bulb tonight. Are these on some sort of circuit(like Christmas lights) where if one bulb goes out it will cause the others not to work? That seems stupid but I've seen crazier things. Any trouble shooting ideas would be greatly appreciated.

[Workin' 4 Toys]

I lost you after (running).... How many lights are "out" total? And how many are working??

[jrcarte78]

Originally Posted by Workin' 4 Toys

I lost you after (running).... How many lights are "out" total? And how many are working??

Sorry, what I call "running lights" would be the trailer lights that remain on while my trucks headlights are on. None of these lights will come on when the trucks head lights are on. That includes the 2 that are in the rear of the trailer(in the same housing as the brake lights), the three that are underneath the boat, and the 2 marker lights that are in front of the fenders.The only lights that work are the brake lights.

I have read some other posts regarding this problem and most folks problems were the trailer's wiring harness that plugs into the truck or the ground. But, in my case, if this harness was bad or there was a bad ground the brake lights would not work, correct?

Thanks W4T.

[Workin' 4 Toys]

If you lost the ground, the brake lights also would not work.
If nothing works, I would first suspect the connection at the truck. The plug. If everything is clear and works, I would then suspect a wiring issue.

I personnally had a wireharness deteriorate within the trailers frame. I could find no evidence at any wire that was visible. I had to pull the harness out of the frame tube to see where the wire had deteriorated so badly, it had seperated. This was an aluminum frame snowmobile trailer.

Perhaps a test at the connector is in order before moving on? If you don't have an tester, perhaps another trailer for a test?

If there is corrosion in the connector, as is the case sometimes, a mixture of baking soda/water would help clean it.

[Workin' 4 Toys]

Was this helpful?

[TMCNo1]

First thing to try is a jumper ground from the trailer (raw metal) to the tow vehicle (raw metal) and see if the lights work properly, them be sure the white wire (ground) is properly grounded to the tow vehicle and to the trailer.

[jrcarte78]

Originally Posted by Workin' 4 Toys

If you lost the ground, the brake lights also would not work.
If nothing works, I would first suspect the connection at the truck. The plug. If everything is clear and works, I would then suspect a wiring issue.

I personnally had a wireharness deteriorate within the trailers frame. I could find no evidence at any wire that was visible. I had to pull the harness out of the frame tube to see where the wire had deteriorated so badly, it had seperated. This was an aluminum frame snowmobile trailer.

Perhaps a test at the connector is in order before moving on? If you don't have an tester, perhaps another trailer for a test?

If there is corrosion in the connector, as is the case sometimes, a mixture of baking soda/water would help clean it.

Thanks. So it sounds like I need to test the connector on my trailer. I will pull the volt meter out at lunch time and test. Possibly the contacts for the lights that are not working are corroded to the point of failure but the contacts for the brake lights are still functional? Sounds like a possibility. I will post after lunch and let you know what I found. Thanks!

EDIT/ I will clean my contacts--obviously I will not be able to test voltage on the trailer connection

[jrcarte78]

Originally Posted by TMCNo1

First thing to try is a jumper ground from the trailer (raw metal) to the tow vehicle (raw metal) and see if the lights work properly, them be sure the white wire (ground) is properly grounded to the tow vehicle and to the trailer.

But the brake lights work great. Wouldn't this indicate that ground is not the problem?

Thanks No1!!

[Workin' 4 Toys]

White- Ground
Brown- Running/Tail
Yellow- Left/Brake
Green- Right/Brake

Test the Brown for power at the "truck" side of the plug, if you have power, then test the brown "trailer" side.

[Workin' 4 Toys]

FWIW- I am going to "guess" and say it's corrosion in the trucks connector. And to go one further, guess the brown terminal has the bad connection.

Again, this is my assumption.