trailer wiring problem

Kansas4010 · Feb 25, 2020

I've never seen this problem before but on my trailer when the left turn signal is on the clearance lights on that side blink as well. It doesn't do it all the time though. The right side doesn't do this. I'm wondering if it is a bad ground somewhere but I've never heard of it acting this way. Any ideas on where to start looking. When I have time I really need to completely rewire the trailer.

Old560 · Feb 25, 2020

Sounds like the wire for the markers has worn through and making contact with the wire for the blinker. Maybe turn on the blinker and then start moving all the wires around to see if you can duplicate the problem. I hate problems like that.

Steve@Advance · Feb 25, 2020

Start at the left tail/signal light.

Bad grounds do strange things.

Could be the socket is corroded, the lamp is not fully seated and crossing the contacts in the base. I've even see the element fail, hang down and cross over to the running light side of the lamp.

Look for taped connections, especially if the running light circuit is taped along side the turn/brake circuit.

NC Wayne · Feb 25, 2020

I'd say change the bulb. I've seen the one of the filiments break and get laid over on the other cause this before.

Kansas4010 · Feb 25, 2020

I really hope that isn't the problem. The wires run inside frame and pipe and aren't even visible.

kcm.MN · Feb 25, 2020

Do the clearance lights blink in unison with the turn signals?

I have a 16' enclosed trailer where something similar happened. There were lights mounted on the aluminum fenders. To the rear, people would see a turn signal/stop light. There was another light in the front side of fixture (amber) that would blink as well. The blinking was not in unison with the vehicle flasher.

Problem ended up being the ground. Lights were attached to the thin aluminum fenders, but normal road vibrations made the sheet metal screws wallow out the holes. I fixed the problem by replacing the sheet metal screws with small machine screws, nuts and lock washers. Haven't had a problem since.

Michael Soldan · Feb 25, 2020

99% of wiring problems is due to insufficient ground. I have done a lot of trailer wiring and I have seen your problem before. The socket may have corroded and lost its ground, the lamp may have lost its ground. I use self taping metal screws and run them through the appliance and into the trailer frame. This provides ground. I have also ran a short piece of wire from the light to the trailer frame for ground. Sometimes a new light is needed as the old one is rusted and the socket is corroded away. Take a piece of wire and ground the socket and see what you have. Remember 99% of failed lights is a ground fault

DoubleR · Feb 25, 2020

Bad ground would be the first thing I looked for.

Russ from MN · Feb 25, 2020

Easy to troubleshoot, run a temporary ground (jumper cable) from the tow vehicle to the bulb socket. If that doesn't fix it then change the bulb.

Goose · Feb 25, 2020

I'd check the grounds.

My trailer lights did bizarre things until I figured out the only ground connection between the tongue and rear of the trailer was through the hinge bolts where the trailer tilts and they had gotten rusty with time. I ran a ground wire around the hinge from the tongue to the main frame of the trailer and the lights work perfectly.

It only took me 20 years to figure that out.

Leroy · Feb 25, 2020

I am with NC Wayne, new bulb. Have had that on vehicals as well as trailers. Easiest thing to do.

DMartin9N-2N · Feb 25, 2020

Good morning! There can be such a thing as a bad trailer light, brand new. I had a light cause several problems, I eventually found the light was assembled badly from the factory. I had removed the small outside bulb from the light (the bulb that serves the side or clearance lens). Unknown to me, the contacts inside the assembly were put together sort of cockeyed, so that if the small side bulb was removed, a direct short was created. After replacing the trailer light with a good one, there were lots of problems finding where the fuse was blown in my tow vehicle. That is a story by itself, for another day.

Dennis M. in W. Tenn.

John T · Feb 25, 2020

AS a used implement dealer and retired farmer Ive see a TON of such trailer electrical problems caused BY A POOR GROUND. If one return path is resistive or open current seeks a path elsewhere and maybe through another light causing it to glow..

CHECK AND REPAIR ALL GROUND CIRCUITS AND CONNECTIONS

Ive also seen rusty resistive corroded bulb sockets cause problems.

Bad ground or bad bulb socket is my best guess, I bet many agree ???

John T

jhwis · Feb 25, 2020

ground

RobCons · Feb 25, 2020

I would start at the lights. Look for a corroded or messed up connection at the bulb. Sounds like the ground is messed up somewhere.

jeffcat · Feb 25, 2020

"I need to rewire" There are several things but all lead back to crummy grounds either the harness, your trailer hitch plug, or in the lamp fixture with crummy build connections. This spring I have all of the parts to redo mine with REAL fixtures. These are Grote fixtures. Picked up at a car show. These Grote lamps are used on Ford,Chevy, Dodge etc. Go on Ebay to find them. Make sure you get the harness part with them. Each style has a different plug type. Also order some RED LED extra bright bulbs. These fixtures also have backup lights. What I did was cross wired the sockets and now both of these RED LED bulbs come on. Very bright tailights. The wire harness from any store has a white wire that goes to the frame by the hitch. I will be running separate ground to each fixture. Yes my marker lamps blink.

caterpillar guy · Feb 25, 2020

Blinking with the turn signal is a bad ground connection. Semi trailers are famous for that problem in the winter mostly due to the salt and corrosion. Then for best lights go get a couple of those 4inch round trailer lights like on semi trailers, They have both options an enclosed grommet you can just feed the wires through a hole to plug into the light or the open version and just plug the wire into the light. I like the open version. It doesn't hold the water moisture in by the light plug. Then with some grease on the plug just make your connections and plug in the light will out last any of those plastic housing lights by years. All those square/rectangle plastic housing lights use a 1157 bulb and corrode in short order inside the housing.
The round grommet lights even have a bracket you can get to mount them on vehicles with.

gene bender · Feb 25, 2020

If it was a bad ground it would not lite

MARK ROBKE · Feb 25, 2020

Does the l/s tail lamp glow bright(like brake light is on), or, normal brightness, or, a bit dimmer than usual tail light? Does your dash turn indicator glow when lights are on? If real bight, it is a bad bulb, or shorted to brake light wiring. If t/s indicator glows in dash it is shorted to t/s wiring. If tail light blinks dimly or not at all , it is bad ground. Bad ground - in this case - will be at/for the rear tail lamp. Could even be the bulb socket it self. Mark.

Pete in Holland MI · Feb 25, 2020

Dad once had a car where when the brakes were pushed, or the right turn signal, the running lights would energize. Problem was narrowed to a leaky tail light assembly that was partially filled with water. There were several tail/stop light bulbs in that housing. One, the glass was cracked, and filled with water. This water made a connection between the brake light fillement and running light fillement. Drove him nuts trying to figure that out.

DERM · Feb 25, 2020

Back when I had my auto repair shop I ran into the same problem nearly drove me crazy ( or more than I was), finally found an 1157 bulb that the brass broke free from the glass and the two small copper wires inside were twisted together. Start with the cheap and easy stuff.

Opey · Feb 25, 2020

I once had a screw from an unused circuit in a plug come loose and get caught between the turn signal and the brake circuit that caused the brakes to lock every time the signal blinked. Took some time to fire it out.

Tim in OR · Feb 25, 2020

Ground --- anywhere from the plug on the pigtail to a dirty socket on the lights. Check your grounds.
Tim in OR

Tim in OR · Feb 25, 2020

with a bad ground in the socket of the tail/stop light, One circuit will ground the other by backfeeding to the other.
Tim in or

Rick Anderson · Feb 26, 2020

I had the same problem on a two year old trailer. Mice got inside the frame and chewed insulation off a bunch of wires. Had to pull all the wires on that side and replace them. About 3 feet of wires were chewed

Blackhole49 · Feb 26, 2020

Tim Cl. · Feb 26, 2020

Make it easy on yourself and replace the wiring.

tlock0331 · Feb 26, 2020

i would start with the blinker fluid, if that is ok i would look at the flux capacitor, from there, maybe a new transmognifier and check the electrical grease in the canooter valve.

let us know what you find.

trailer wiring problem

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