ckchan10

Hi all,

I recently purchased a 4' tire trailer from Harbor Freight and hooked up the wiring through a harness I got from Etrailer.com.

The issue I am running into is that when I turn on my vehicle lights (for nightime driving) the tail lamps on the trailer are illuminated; but when I push on the brake pedal the trailer brake lights turn off. Everything else works as it should except this one issue. Without the lights on (during the daytime) everything works exactly the way it should. Did anyone else run into this problem and if so how did you fix it?

Thanks!

ckchan10

This is the trailer I am using.

ErnieN85

Bad ground connection, or missing completly

1stz51

If I remember, I had a wire harness hookup on the car side that I
got from etrailer. had to replace that wire harness hook up, it was bad.
Mine had exact same problem

Bill R.

ckchan10

I did the grounds on both the car and trailer exactly as illustrated on the instructions but I'll double check it. Thanks.

ckchan10

How did you pinpoint the problem back to the harness on the car side? Is there any way to confirm other than ordering a new one? Thanks!

c4cruiser

The white wire on the trailer harness (both ends) is the ground wire. Make sure that the ends are connected to a good ground source such as the car frame and trailer frame.

Brake lights on the trailer turn off?? Are you saying that the brake lights on the trailer do not illuminate at all? What about the turn signal lights on the trailer; do they work properly when the tail lamps are either on or off?

ckchan10

There is only one white wire on the trailer harness. I attached it directly to the frame just as the instructions stated.

If the lights on the car are off, then the only lights on the trailer that are illuminated are the side lights. The brake lights will work if I push on the brakes. The turn signals also work.

If the car lights are on, then the side lights and brake lights are also illuminated. The turn signals also work. But when I push on the brakes the rear trailer lights turn off (basically the exact opposite of the car lights).

ErnieN85

Check the ground on the tail light assemblies

harrydirty

I used to pull a Harbor Freight trailer with my c6z. I did not use any converter module, hooked up harness directly to brake light harnesses using 3M taps. Assuming you have the same standard flat 3-pin connector with 4th ground pin, convention should be (on both car and trailer):

Green=right turn/brake
Yellow=left turn/brake
Brown=running lights, side lights, license plate light
White (mine is brown/yellow)=ground

Check to make sure everything is hooked up correctly, especially how you have tapped into the car harnesses. I did not trust using the trailer frame for ground, so I ran separate ground wire to all lights. This was easy for tail lights, but pita for side lights, but I believe this will be a better long term solution.

If I had to do it over, I would not tap into my harness using 3M taps. Instead, I would use the harness sold by Curt. It plugs directly into the factory connectors so no need to cut, splice, or tap. It is Curt part number 56014 and is listed at $26.23.

This is pretty straightforward, so take your time and double check all connections, you will probably find something overlooked. If you have access to a multimeter, that will help confirm correct/good connections.

Good luck with the troubleshooting.

ckchan10

Will do. Thanks for your advice.

stuiephoto

The HF trailer I built had the grounds built into the mounting studs, which grounded to the tail light brackets. The issue here is that with the way the bracket mounts, the bracket doesnt ground well to the frame due to the red coating. I Just ran a self tapping screw through the bracket into the frame to complete the ground and it fixed all of my issues.

c4cruiser

Something is wrong in the wiring. With the car lights off, no lights should be illuminated on the trailer. With the car lights on, the trailer tail lamps, side lights and license plate light should be on. The brake lights on the trailer should only work when the pedal is depressed or when the turn signals are in use.

The only wires that should be used on the car are one wire that illuminates the tail lights, a single wire for the left brake/turn signal and another for the right brake/turn signal. Double check what wires you are using on the car side. The tail lamp wire should be the same color on both the left and right lamp harnesses. The brake/turn signal wires will have different colored wires on the left and right.

The white wire that is part of the harness for the car side should be attached to a good ground location on the car. You can use a ground wire that is part of the tail lamp wiring or even the license plate wire harness. Or better, find a steel or aluminum bracket and use a self-tapping screw for the white wire. These screws works great for getting a good ground. Use a ring terminal to terminate the white wires.

Another thing you may have noticed is that the turns signal lights will flash rapidly if the trailer light bulbs are the standard incandescent style (1132 bulb). Change the trailer bulbs to an LED bulb and that will solve the "hyper-flash". Beats having to locate and swap out the car's turn signal flasher with an electronic version.

Bill Dearborn

I agree. When you get weird things happening with car/trailer lights check the grounds. It is a basic rule of thumb. It sounds like the tailights are getting their ground connection by way of a sneak circuit connection through the stop light circuit and when you hit the brakes you are applying 12V to both ends of the circuit so current stops flowing and the lights go out. Do you have a good ground through the trailer/car harness connection? You don't want to depend on the trailer hitch providing a good ground. One way to check is to disconnect the trailer from the car hitch but leave the electrical connection in place. Then using your DVM in continuity mode check to see if you have a circuit between the frame of the trailer and the car by touching one lead to a good ground point on the trailer and the other on a good ground point on the car. If you get a weak signal switch to ohms and see how high the resistance is. With a wire between the two the ohms should be very close to zero.

Bill

ckchan10

I finally got it sorted out...it was the ground on the car side of the harness. The ground location shown in the etrailer.com instructions does not work very well. I did spend a lot of time on the trailer grounds but the culprit ended up being at the car side.

I want to say a big THANK YOU to everyone who responded and provided their input.

Thanks!
-Danny