No lights on the Trailer there is but power at the Wires

[KM7]

No lights come on on the trailer!! I have checked that I have power in the harness. There are 3 connections: From the round plug at the back of my 4Runner, all signal good: Tail lights and both right and left turn signals. That harness only goes about 2 feet and then through another 4 pin connector. I checked the output at THAT connector, all good: White is ground, Brown is tail lights. Yellow Left turn, and Green right turn. I even stab into the wire with a pointed signal tester and it works. The test light comes on. I still get no lights on the trailer???

What can I check next?
Any suggestions?

Thanks
Thanks

 

[JimS123]

What can I check next?

The power at the socket. If it's powered there the bulbs are no good.

Also, I assume the trailer coupler was attached to the car's ball when you were testing.

 

[roscoe]

Ground wires, ground wires, and ground wires, are the 3 most common problems with trailer lights.

 

[04fxdwgi25]

Ground wires, ground wires, and ground wires, are the 3 most common problems with trailer lights.

And NEVER use / depend on the trailer ball for the ground between the vehicle and trailer.

 

[Chris1956]

Check power at the bulbs. The sockets often corrode. In the old days I would solder the wires to the bulbs and coat 'em with grease to keep the corrosion down. Luckily for me, now I live 1.5 mi (all back roads) from the ramp, so I don't use the lights.

Also, it pays to d/c the trailer lights before backing the trailer into the water. Otherwise, the hot trailer lite bulbs hit the cold water and they often crack.

 

[dingbat]

Also, it pays to d/c the trailer lights before backing the trailer into the water. Otherwise, the hot trailer lite bulbs hit the cold water and they often crack.

Only applies to open frame (RV style), incandescent lighting.

You will have no problems with sealed, LED lighting.

 

[rxl650]

My small boat trailer has a tilt feature that caused me hours of head scratching. While trouble shooting, I leaned on the boat while talking to my wife and noticed the lights flicker. Cleaned up the tilt joint and problem solved. Had the same problem on sled trailers also.

 

[KM7]

Problem Solved!! I had a bad ground wire, That makes sense because that can affect every circuit and all the lights on the trailer were out. It was a little strange: I have a circuit tester. It has an alligator clip for the ground and a pointed tip. If you touch anything with power the light comes on. See attached. I had good power and good ground going into the last connecter and I inch after the connector but still no lights.

I stripped the ground wire another 2 ft back where all the grounds come together and there was no ground!! To confirm that was the problem, I jumpered from that, bad ground to a know good ground and...All the lights came on.

Solution: splice in a new ground wire using a butt splice. Then I sealed the splice with liquid tape.

So far everything is working again

 

[KM7]

And NEVER use / depend on the trailer ball for the ground between the vehicle and trailer.

Nope. I have a dedicated ground wire at the plug at the back of the 4Runner

 

[KM7]

Only applies to open frame (RV style), incandescent lighting.

You will have no problems with sealed, LED lighting.

Mine are all LED now but not having power in the circuit might be a good idea.

 

[ratdude747]

My small boat trailer has a tilt feature that caused me hours of head scratching. While trouble shooting, I leaned on the boat while talking to my wife and noticed the lights flicker. Cleaned up the tilt joint and problem solved. Had the same problem on sled trailers also.

This is why on all of my "good" trailers (14' 7000lb car hauler + boat trailer) I rewired them with dedicated ground wires... can't stand chassis grounds on exposed bolts. Although finding lights that don't require such can be a pain- submersible LED lights seem to be universally this way,, but marker lights are a crap shoot.