Trailer lights not working at all - help!

sacjon

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Joined
Oct 19, 2007
Messages
10
I bought a new set of light fixtures (to replace a busted one) and wired them to the trailer's existing wiring. I also bought a little tester that was recommended in a few posts to check the tow vehicle's wiring - it checks out fine. But when I hooked up the trailer, only the right side light fixture worked (all functions) - the left side did not work at all.

So, I figured I would first check the white ground wire on the trailer - it was attached to a rusty bolt on the coupler by only a few bare strands of wire. So, I removed it, cut it, and stripped a new section of clean wire. I attached it with a clean bolt to the trailer frame and tried the lights again. Nothing! Neither light works at all!

Did I not attach the ground wire properly? Did I blow a fuse?
 

tashasdaddy

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Nov 11, 2005
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51,019
Re: Trailer lights not working at all - help!

possible blown fuse, but if tester show good, it's in the trailer. i solved my lighting problem 20 years ago buy extending the white wire to all the fixtures, one mount bolt. that way there is a direct ground, you don't have to worry about a rusty connection. is the white wire grounded on the car side.
 

djvan

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May 3, 2003
Messages
411
Re: Trailer lights not working at all - help!

Make sure your ground is wired through the tow vehicle's harness. Try to hook a jumper wire (I use a pair of jumper cables) from a good clean ground on the trailer to a good clean ground on the vehicle. I have found (like others) that a lot of lighting problems are ground related. That doesn't mean that is your problem herre, but it is a good place to start.

HTH's

DougV>
 

gunner1

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May 13, 2006
Messages
375
Re: Trailer lights not working at all - help!

DO what I did: Go to whatever store you have locally that sells new trailer lighting kits and replace everything. I went to Gander Mountain and got the Optronics kit that includes the wiring harness ( make sure it's the four flat that you need ) and two complete sealed LED light fixtures that include lights, brakes, left and right turn signals and reverse lights. The left light also has the light to illuminate your license plate. They even include a new plate bracket. All for just $50!! And since they are LED's, they use less power and won't burn out and are alot less likely to go out due to vibration or bumps. Buying that tester was a great choice because now you know where your problem lies.
 

sacjon

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Oct 19, 2007
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Re: Trailer lights not working at all - help!

I bought a new kit but only used the fixtures - I think I might just rewire the whole thing today.

But basically, how / where is a good place to attach the trailer ground wire to the frame? In other words, how do I ground the trailer using just the one white wire (not grounds to all fixtures)?
 

Bondo

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70,465
Re: Trailer lights not working at all - help!

Ayuh,......

Trailer Frames are Metal,+ Metal conducts electricity.....
Attaching the Ground to where it is Now, Should work just fine......
Provided that the trailer frame is conducting the electricity,......
Use your Test Light,+ See if this is the case,.....
If Not,.....
You might have to add more grounding wires, where ever the frame Isn't carrying the load......
 

gunner1

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May 13, 2006
Messages
375
Re: Trailer lights not working at all - help!

I bought a new kit but only used the fixtures - I think I might just rewire the whole thing today.

But basically, how / where is a good place to attach the trailer ground wire to the frame? In other words, how do I ground the trailer using just the one white wire (not grounds to all fixtures)?

The fixtures don't have ground wires? The kit I bought had a brown wire, and a yellow wire on the left side for the lights plus a white wire for ground. The right side had a brown wire, a green wire for the lights and a white wire for ground. I wasn't aware this wasn't normal. Sorry.
 

sacjon

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Joined
Oct 19, 2007
Messages
10
Re: Trailer lights not working at all - help!

Ayuh,......

Trailer Frames are Metal,+ Metal conducts electricity.....
Attaching the Ground to where it is Now, Should work just fine......
Provided that the trailer frame is conducting the electricity,......
Use your Test Light,+ See if this is the case,.....
If Not,.....
You might have to add more grounding wires, where ever the frame Isn't carrying the load......

Yes, I am well aware of the concept of attaching the ground to the frame because of the conductivity. My question is HOW do I attach it? As of now, it is not attached to anything. For example, do I just tape the exposed wire to the metal (probably not), do I wrap it around a bolt on the frame, solder it, etc?

And the light fixtures I have do not have separate ground wires - they are grounded by the bolts that attach them directly to the trailer.

So, first thing I need to do is attach the main ground wire to the frame - any suggestions?
 

wire2

Lieutenant Commander
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Jun 25, 2007
Messages
1,584
Re: Trailer lights not working at all - help!

How old is the trailer? Is there any rust where the side rails bolt to the tongue? If so, you need to either take that joint apart, clean to bare metal, coat with grease and bolt together again. OR extend the white wire from the connector to the lamps, as has been mentioned.
 

sacjon

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Joined
Oct 19, 2007
Messages
10
Re: Trailer lights not working at all - help!

Yeah, the bolts to the tongue are pretty bad - that's where it was attached before and I was having weird light issues. There are, however, a couple smaller holes near the tongue assembly but I cant get a screw or bolt to hold fast in there.

Let's say I do run the ground back to the lights - do I run one white wire to each light? And where do I attach them - to the bolts holding the lights on the trailer?
 

wire2

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Jun 25, 2007
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Re: Trailer lights not working at all - help!

....
Let's say I do run the ground back to the lights - do I run one white wire to each light? And where do I attach them - to the bolts holding the lights on the trailer?
Yes. Those bolts are the ground connection to most trailer assemblies. A few have a ground lead.
Crimp a ring or fork terminal on the wire, apply a bit of grease to the surface to stop future corrosion and do it up.
 

a70eliminator

Captain
Joined
Sep 9, 2007
Messages
3,688
Re: Trailer lights not working at all - help!

Ayuh,......

Trailer Frames are Metal,+ Metal conducts electricity.....
Attaching the Ground to where it is Now, Should work just fine......
Provided that the trailer frame is conducting the electricity,......
Use your Test Light,+ See if this is the case,.....
If Not,.....
You might have to add more grounding wires, where ever the frame Isn't carrying the load......

I agree with all you say, however you are relying totally on the hitch ball connection to ground the trailer to the vehicle, if you run the ground wire from the plug all the way to the light grounds themselves you eliminate the need for ground at the hitch ball, in fact your lights should work without the ball even touching the tow vehicle, I got tired of having to shine up the hitch ball and coupler and just ran the ground all the way to the light, no more problem with rusty hitch ball and grounding.
 

sacjon

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Joined
Oct 19, 2007
Messages
10
Re: Trailer lights not working at all - help!

Hooray!

I fixed it - all lights are fully working now. I grounded the trailer by crimping the ground wire into one of those connectors that go over bolts and then found a small hole drilled in the side of the frame behind the hitch coupler and screwed it in. Now everything is lighting up as it should. So I am going to secure the wiring so it doesn't strain, drag or get pinched anywhere and hopefully I will be good to go!

Thanks for all the tips!
 
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