Just checked my trailer lights and noticed an issue.

The traiiler "running lights" do not come on, when I turn on SUV headlights ? All lights of SUV working, no issues.

Trailer "directional" lights working properly. Trailer "brake" lights work OK.

If it were just the bulbs, then it would have to be bulbs on "both" sides of trailer ? I also have "side mounted" lights on trailer, and they do not appear to be working either ?

Any ideas, why the trailer "running lights" are not working?

Thanks in advance!

make sure your two connectors are both clean,I just tried my lights and saw a similar situation so I cleaned both connectors and now all lights are woking

lights
 

A lot of times the wires in the connector on the trailer that connects to your truck or SUV will become loose, I think worse case put a new connector on if that does not work, put a new harness on the suv, a lot of times all it does take a is a cleaning

If you are mechanical at all, the first thing you need to do is determine if there is power for the running light circuit at the rear trailer plug on the vehicle. You can either use a 12 Volt test light or a voltmeter/tester. Once you've determined that, we can help you from there. Also, the type of vehicle and whether or not it has the factory towing package will be helpful info. (GM has a specific issue in late model vehicles with the tow package)

Blue Thunder

Trailer Light Question
 

Thanks for the info. I'll clean all terminals from SUV and trailer.

How would you suggest I clean the terminals on the SUV side as these are the "female" end, and probably "live & hot" ! I was thinking a "Q-Tip" would work ?

FYI... SUV is a 2005 Ford Explorer, with factory towing package.
The plug from SUV is the typical "blade" type connection, with I believe 3 female, and 1 male connections.

Thanks,
Bigdog

If the directionals work on both sides, you are fortunate; that means only the brown wire is not connecting properly. Ought to be an easy fix.

Some of the side mounted lights are sometimes only reflectors.

This happened to me earlier this month. Even though it has a snap-close cover, the plug on my pickup was carrying more than its fair share of the byproduct of 'mud season'. A shot of compressed air solved the problem.

Hopfully it's just a connection at the plug
Some spray electrical contact cleaner should do the trick
A little dielectric grease (tune up grease) will prevent the problem in the future
If the problem is in the trailer check where the plug pig tail connects to the running light wires (the brown wire is for running lights) this is the likely place since none of the running lights work
good luck
Pirk

clean the connectors!
 

I go through this almost every year. The connector on my Ranger gets corroded from the Winter driving (salt). My DVM will read 12 vdc although it doesn't make it through to the trailer connector. Clean all contacts well!

Trailer Light Question
 

Just to provide the Forum with feedback about my original problem with Trailer "running lights"... Identified the problem !

It was actually a two-part solution:

1. I had a poor Ground connection. I added a new piece of 14 gauge wire,
and bolted the end directly to the trailer trailer frame.

2. 20 Amp fuse blown
My 2005 Ford Explorer has a specific fuse for 'trailer tow parking lamps'.
Know I know..... Explorers' has two fuse panels: one in the usual place
under the dash on driver's side, other fuses in what they call the
'Power Distribution Box', located in the engine compartment.HIGH VOLTAGE
This was where I found the 'blown' 20 Amp fuse.

Anyway, all is well ! Thanks everyone for their information.

Trailer Light Question
 

The new 10amp fuse fcorrected my "running lights" problem, as they now work, but now I have another...... :(

My left directional on trailer works, but only if I don't put on the headlights.
If I put on the head-lights, the running lights work ok, but the left tail-light doesn't come on, nor does the left directional work on trailer.

Is this just a "bulb problem" ?

Thanks in advance !