Trailer Running Lights not Working

As title, my running lights are not working. Brakes, flashers, signals all work but noticed this AM the fender markers and rear all time lights are not working. Ground is fine and showing voltage. Any ideas? Not too familiar with trailer lighting.

 

Are the lights led’s? How long have you had the trailer and have the lights worked previously?

 

Yes LED. 5 months bought brand new. Lights worked up until I just noticed them.

 

Hmmmm....sometimes led’s can be intermittent in my experience. I replaced my trailer lights with LED’s and some didn’t work. Replaced them with regular bulbs and they worked immediately. Not sure if it has something to do with the the electrical draw but just a thought.

I would also try to clean up the ground wire (sandpaper to a shiny finish) and reinstall.

 

Usually if some lights work but other do not it is corrosion or crud on one of the terminals, either on truck side or trailer plug. There should be no residue in either plug so if you see any discoloration clean it up.

 

Do you turn on the headlight on the truck? The running light/fender markers won't turn on on my trailer if I left the head light switch in auto. Also do a google search for "keep RV lights on trick", there's a youtube video shows how you could "turn" the running light/fender markers on from the 7-pin cable from trailer. Then you could find out whether the lights are working or there's anything wrong with the wiring/connections.
Good Luck!

 

Yeah I ground it down to bare metal and no dice.

I checked both plug and truck side but didn't see anything. May be something deep in the terminal I'll have to get with some steel wool.

Lights on auto always worked. I just tried turning them on manually and still nothing.

 

Did you try the trick on youtube to connect the two contacts on the trailer's 7-pin to turn on the lights on trailer?
If it doesn't work, you might have some loose connection or blown fuse on the running light circuit.
If it does work, the porblem would be the 7-pin socket or the wiring to the 7-pin socket on the truck.

 

Its a 4 pin.

 

If you have access to a test light check to see if there is power where the brown wire connects on the truck side. The other thought is to take a battery and supply power to the trailer plug. Negative to white and positive to brown wire. If it works you might have a blown fuse. Not sure if Toyota use's a fuse or has gone to circuit breakers that reset when the engine is shut off.