Let me know if it would be better to post this on the outdoor board.

Having a lot of issues with my utility trailer lights. At best, I've had running lights and right brake/turn signal. At worse, I have no lights. I can't get the left brake/turn signal to work at all. I'm pretty sure it has to do with the ground because I've had other times where I've had a weak left running light and when I put my hand on the trailer it brightens to full strength or had no right brake/turn but when I put my hand on the trailer it comes on. I've crawled from front to back to look for fraying or cuts. My next step will be trying to improve the ground at the lights and tongue. Is there anything else I should be looking for? What's the best way to ensure I'm getting good grounds at all three places?

Thanks.

Stupid question but do you have the trailer hooked up to the truck and is it properly grounding?

Yes it is hooked up to the truck. As posted earlier, I believe the issue is with the ground and unsure how to resolve it. That's why I posted what I posted.

Just guessing at your style of light, but most of those fixtures ground via the mounting bolts. Try taking the lights off, cleaning the bolts and trailer with a wire brush and reassembling.

They are LED lights so they have their own ground. I know it is a grounding issue. When I shake the trailer the light will come on or at least flicker. With that I am assuming it is at the ball?

Where is the main ground wire terminated? Onto the trailer frame or going into the plug? Could be rusted ball usually that'll go away with a short drive.

ITs ground to the trailer at the tongue and both lights have their own ground. I'm in the process of brushing/cleaning all of the grounds, connections and the ball and receiver. We'll see if that fixes it.

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What's the best way to ensure I'm getting good grounds at all three places?

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Crawl under your trailer and see where the ground wire in the harness terminates. Your wires for the left and right housing go all the way to the back of the trailer but I wouldn't be surprised if your ground wire terminates 1/3rd of the way back and is grounded to the trailer.

That connection can get crud on it as well. I had one side that wouldn't get a good ground so I ended up running a dedicated ground wire from the drivers side light back to where the harness ground wire was grounded.. That solved my issue.

Ok. I will try to be as detailed as possible so bear with me.

My trailer is a 4 flat. Out of the 4 flat connector I have 5 wires:

1. White - ground that is bolted to the trailer frame about 18 inches behind the ball receiver on the tongue

2. Brown - running lights for the passenger side

3. Gray - running lights for the driver side

4. Yellow - turn/brake for passenger side

5. Green - turn/brake for driver side

Both tail lights have the corresponding wires for running lights and turn/brake and their own white ground wire. The driver side has its own dedicated bolt for the ground wire separate from the mounting bolts while the passenger side is grounded to one of the mounting bolts.

I have throroughly cleaned and brushed with a wire brush all bolts, nuts, connector rings (including replacing the connector ring and bolt at the font of the trailer) and the ball and inside of receiver.

I have spotty running lights at best that flicker when you shake the trailer and no turn/brake lights at all.

Any other suggestions? I'm afraid that there is no point in rewriting the whole trailer when I know the issue is the ground somewhere. I'm 99% certain it's at the tongue/ball, but I don't know how to solve it.

I have a guy in Pasadena that does mobile trailer repair if you near SE Houston.

Flickering lights when the tongue is shook is the tell tale sign of a faulty ground / trailer trying to ground through the ball. The ground connection opens and closes as the position of the ball changes inside the hitch on the trailer, causing the lights to flicker on and off.

Is the plug on the pickup side grounded? I fixed my brother in laws issues when i discovered the ground wire going to the terminal in the back side of his pickup plug was broke.

You need clean, bare metal for your eyelets and bolts to touch to make a connection on your trailer frame to complete the ground. Use a wire brush on the hole where your ring terminal attaches on the frame of the trailer. Also, take a screwdriver and scratch up the area around the hole. You need shiny metal to make it work. I have switched several trailers from a nut and bolt to a self tapping screw to secure the ring terminal to the frame. That way you know your ground is going into the frame of the trailer.

I'm in central Texas, but thanks.

Sounds like you are grounding through the plug, not through the ball. Maybe the ground wire on the truck side going into the plug is bad.

Try a jumper wire from bare metal on truck to bare metal on trailer. If lights are solid, you know it's the ground coming through the plug.

I checked my truck this morning. Used a circuit tester and clipped the ground to the ground on the 7 pin and tested run lights, left and right turn signals, plugged in my 4 flat converter and clipped ground to ground and tested all three lights. The lights worked both ways I tested it. That tells me I can safely assume there is no issue with the truck itself correct?

My ground at the tongue is washer, ring connector, washer, bolt head. Any issues there? I also tried it with no washers with the same result. The last thing I am going to try is a self tapping screw instead of a bolt. If that doesn't solve it I'm going to rip all the wiring out and rewire the whole trailer.

I think you're getting it narrowed down. I suspect the connection of the ground wire to the frame at the tongue -- the ring terminal.

Try this, unbolt the ground ring, scuff the trailer frame underneath the ring to bare metal. Before replacing the bolt, wrap the bolt with bare braided copper wire (just an inch of stripped trailer wire) so that it is pinched between the washer and the trailer. The multiple points of contact of the copper braid will improve the ground contact. This is an old welding trick to improve ground clamp conductivity.

Ground jump on tilt trailer

I was checking out wiring kits online and found this install video of a rewire of a tilt trailer. My trailer is a tilt trailer with a wood deck. I did not realize a tilt trailer would need the ground jump they talk about at the 3:45 mark. Could that be my problem? My trailer does not have that, but has worked for the past decade until now.

The video is on the page of the kit I was looking at.

And then I also found this.

Tilt trailer grounding issue

If it grounds anywhere behind the hinge it could be your issue. I believe you mentioned the rear lights had ground wires that went to the front of the trailer to ground. If that is the case then you don't need the jumper wire.

What happens on a tilt trailer that is set up where the lights ground rear of the hinge is similar to the trailer trying to ground through the ball hitch. The metal in the hinge vibrates so it isn't always in good contact to complete the ground. Sometimes it is, and sometimes it isn't so the lights will flicker.

Make sure your ring terminals on your ground wires are touching clean, bare, shiny metal or are attached via self tapping screws. Also, if you have ground wires coming off the rear lights, make sure those have continuity from the light to the ring terminal, and make sure they are attached to the tongue of the trailer in front of the hinge.

I have made jumper wires to bypass the hinge. All you need is a short piece of wire, 2 ring terminals, and 2 self tapping screws.

UPDATE

DISCLAIMER: TAILLIGHTS ARE LED

I added a ground wire between the tongue and the bed frame and my grounding issues are gone. Bright solid running lights with no flickering when bumped or shaken. Thank goodness.

Now the problem is I have right turn/brake, but no left turn/brake. I went back to the light and undid the turn wire and twisted the light wire and trailer wire together. No luck. I've already checked the fuses on the truck.

I will admit the left turn/brake hasn't worked at all since I picked it up from my uncle's a couple of weeks ago so I'm not sure how long it's been an issue. He mentioned the left light was spotty when I picked it up.

Could the light itself be bad? A loose connection inside the light casing? Can I take the light somewhere to test just the light?

You can take the light to the battery your pickup and test it there. One wire on the hot, and one on the ground. The light should come on.

You can spend $2 on a test light to see if you are getting power to it.

The running light works. I'm trying to test the turn/brake signal. Can I do that with my truck battery?

Willis said:

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The running light works. I'm trying to test the turn/brake signal. Can I do that with my truck battery?

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yes, as long as you have 12v positive and a ground.