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View Full Version : Trailer Lights not Working; Am I an idiot? Please help.


jrcarte78
07-11-2007, 10:53 AM
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.

:confused:

Workin' 4 Toys
07-11-2007, 10:59 AM
I lost you after (running)....:confused: How many lights are "out" total? And how many are working??

jrcarte78
07-11-2007, 11:06 AM
I lost you after (running)....:confused: 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
07-11-2007, 11:48 AM
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
07-11-2007, 12:01 PM
Was this helpful?

TMCNo1
07-11-2007, 12:04 PM
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
07-11-2007, 12:17 PM
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 :o

jrcarte78
07-11-2007, 12:19 PM
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
07-11-2007, 12:31 PM
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
07-11-2007, 12:33 PM
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.

06' X-2 R8R H8R
07-11-2007, 12:46 PM
Change the fuse in your auto, it happened to me also. The main fuse box has a trailer lights fuse, check that one.

trickskier
07-11-2007, 12:58 PM
Are you using a 7 way round or a 5 way flat connection???

jrcarte78
07-11-2007, 12:59 PM
Change the fuse in your auto, it happened to me also. The main fuse box has a trailer lights fuse, check that one.

I thought of this but then thought again, b/c the brake lights were still working.

Workin' 4 Toys
07-11-2007, 01:00 PM
trick.....'89...I'd guess a 4 way flat..

Workin' 4 Toys
07-11-2007, 01:02 PM
I thought of this but then thought again, b/c the brake lights were still working.
This will be part of the test at the connector.....;)

jrcarte78
07-11-2007, 01:05 PM
Are you using a 7 way round or a 5 way flat connection???

Here is my adapter--

mayo93prostar
07-11-2007, 02:32 PM
another test you can do is to use a battery charger to provide power to your trailer and hook the black clip to the ground pin and then touch the red clip to one of the other 3 sockets and test which lights come on per the color code defined above. be carefull not to touch the two clips together or sparks fly. I use smaller alligator clip wires for this test. this way you are testing the trailer independent of the vehicle. you can test the vehicle with a test light or volt meter. test light is better if available. you may have voltage but bad wire that does not provide enough current under load. poor ground can be a factor too even if the brake lights work. I also have a little black plug that plugs into the vehicle 4-way flat connector with red lights on it that tell if each signal is good. you should be able to get this from an autoparts or marine store. good luck.

trickskier
07-11-2007, 03:09 PM
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.
You said you have a volt meter. A test light would be easier to use in this scenario..........In addition to the above...........Plug your adapter in and test it too without the 4way flat connected..........I have also found the flat connectors to go bad so if the adapter tests OK........Plug the 4 way into the adapter then test the brown wire coming out of the flat connector.

Those 7 way round adapters sometimes don't make good contact when plugged in. You may have to (carefully) bend the prongs inside to make a good connection.

Good Luck.............:D

SDAhockey21
07-11-2007, 03:15 PM
Or to see if the problem is with your auto hook this baby up

http://www.trailertester.com/images/01949.jpg

RV Flat 4-Pole Plug Tester

• Tests Output of towing vehicle's lighting plug.
• When the customer says "Trouble's not my truck, it's in your trailer", show him!
• Pocket sized- weighs only a few ounces
• An essential tool for shops doing hitch and lighting connection installations.

jrcarte78
07-11-2007, 04:15 PM
O.K.--I pulled the volt meter out and tested the connections. It seems the problem is the truck not the trailer--guess I should apologize to the trailer for whaling on it last night HA! j/k :rolleyes: . I got voltage at all the connection points except the running lights terminal. I did not have time to keep working my way back. I'm hoping it's simply a short at the next harness point towards the front of the truck. There is another connection point 12" - 18" back up towards the front of the truck. My truck did take a nasty slide backwards down the hill that is our driveway over the winter(a story for another thread :mad: ) and got slammed pretty good into the ditch. I'm wondering if that didn't loosen or damage that wire in some way. I'm going to keep working w/ it tonight and see if I can't remedy the problem.

In case anyone want to know the truck is an 02 Silverado ext cab Z71 w/ 5.3 and GM tow package.

Thanks for everyone's responses and input. I really appreciate it. I will definitely let everyone know what comes of it. Thanks again!

jrcarte78
07-12-2007, 11:14 AM
In answer to my own question.....

I am an idiot....:rolleyes:

There is not just one fuse related to trailer wiring. I had checked the fuse in the truck's cab fuse panel. It was fine.

Then I started looking a little bit closer at my truck's owner's manual.

The culprit was the trailer wiring fuse in the engine compartment fusebox.

Thanks for everyone's responses.

If anyone needs any help getting their trailer lights to work, just remember, I'll be here :o

loeweb
07-13-2007, 09:12 PM
I am having the same problem. I think I may have the problem found. I too had no clearance lights but everything else was fine. Found out it was a blown fuse because one of the clearance lights was missing and some idiot (woops) straight wired the hot wire to the ground and kept blowing fuses. Have not found the right size bulb housing to fit the bracket on the trailer, but have replaced all the clearance bulbs that were bad. Still no clearance lights. Is the missing housing the problem or do I need to look elsewhere?

TMCNo1
07-14-2007, 09:43 PM
Is it a MC trailer?
As long as I can remember, MC has used sealed waterproof lights on the entire trailer. Bulb replacement as in a auto is not a option, but you have to replace the entire light.

jrcarte78
07-18-2007, 11:16 AM
Is it a MC trailer?
As long as I can remember, MC has used sealed waterproof lights on the entire trailer. Bulb replacement as in a auto is not a option, but you have to replace the entire light.

Only one of the lights (port tail light) on my trailer is the sealed waterproof variety. All the rest are automotive style bulbs. I think the person who had my boat before me made some modifications to the trailer. I just make sure to unplug my lights before I put the trailer in the water.

TMCNo1
07-18-2007, 11:31 AM
Only one of the lights (port tail light) on my trailer is the sealed waterproof variety. All the rest are automotive style bulbs. I think the person who had my boat before me made some modifications to the trailer. I just make sure to unplug my lights before I put the trailer in the water.

Apparently someone didn't understand boat trailer lights and just replaced them with the first thing they could find. Overton's, Boaters World, West Marine, Northern Tool and even Wal-Mart carries all the basic sealed waterproof, tailights, clearance lights, sidemarker lights fairly cheap now that LEDs are getting cheaper and becoming more commonplace.

jrcarte78
07-23-2007, 05:06 PM
Apparently someone didn't understand boat trailer lights and just replaced them with the first thing they could find. Overton's, Boaters World, West Marine, Northern Tool and even Wal-Mart carries all the basic sealed waterproof, tailights, clearance lights, sidemarker lights fairly cheap now that LEDs are getting cheaper and becoming more commonplace.

Agreed. The prior owner of my boat was in a hurry to get everything done evidently. Nothing major has been wrong yet..... I'm keeping my fingers crossed.

EFiles
03-30-2008, 12:56 PM
In answer to my own question.....

I am an idiot....:rolleyes:

There is not just one fuse related to trailer wiring. I had checked the fuse in the truck's cab fuse panel. It was fine.

Then I started looking a little bit closer at my truck's owner's manual.

The culprit was the trailer wiring fuse in the engine compartment fusebox.

Thanks for everyone's responses.

If anyone needs any help getting their trailer lights to work, just remember, I'll be here :o


I too am an idiot. But with the help of this board I am able to get by. :D