Trailer Connection Plug

[RUSSELL5000]

I noticed that the running lights on my travel trailer were not working on Saturday; on Sunday I noticed that the running lights on the boy scout trailer were not working. Both days were bright and clear and I was only travelling during the day so no big deal.

I got my voltmeter out last night and there was no voltage on the pin in the seven pin round connector in the bumper of the truck for the running lights; there was also NO voltage for the running lights in the rectangular four pin connector. There was voltage for the brake lights and the voltage jumped up and down with the turn signals. This all makes sense to me because the brake lights and turn signals worked on the trailers but the running lights did not.

The running lights have worked in the past and so I thought the connection underneath the truck must be loose. I pushed together but no change.

I can't figure out how to unplug the plug at the end of the wiring harness from the plug-ins in the bumper - I am afraid of breaking the plug at the end of the wiring harness. Does anyone know what the trick is?

I figured I would take my voltmeter and test the plug at the end of the wiring harness once I get it loose. That would tell me if the problem is farther back in the harness or at the plug.

Not sure where I would go from there. Has anyone else had this problem?

Thanks!

 

[RikDavis]

Is there a fuse for the running lights under the hood? There are fuses in the 2013.. The fuse is F29.
There is a good electrical description in some posts by Kirwin around the end of last year or the beginning of this year, i cut and pasted some of the info but don't have the thread name.

If the 2012 is similiar it might help you out

 

[Kirwin]

Here you go. Or see page 118 in TDR issue 84. https://www.turbodieselregister.com/threads/246275url] This is for a 2013 or 2014 truck. I'm not sure that the 2012 is the same. Ken Irwin

 

[RUSSELL5000]

Thanks, guys.

I did some more testing and found a blown fuse; it was a 20 amp fuse. I replaced the fuse and now I have power at the pin in the connector.

This suggests to me that the travel trailer must have a short to ground somewhere in the running lights circuit. I'll be looking at the travel trailer tonight with my volt meter.

 

[jelag]

Something you might consider if you tow a lot... I took a piece of 8 gauge wire and ran it from the battery to the 12V pin on the plug and than from the trailer plug to the batteries... and of course a ground wire... the first thing I found was that my lights on the trailer were brighter... and I was able to keep my trailer batteries at a higher level of charge... But if you camp at night you need to disconnect the connector to prevent the draining of your truck batteries.

 

[JDancoe]

If you re going to run a direct 12V lead to the trailer charge circuit, install a relay or Constant Duty solenoid that is energized by the ignition circuit and it will open the circuit when the truck is turned off, and prevent tow vehicle battery drain.
I always install as large a ground circuit wire as I can force into the back of the connectors. You can NEVER have too good a ground circuit!
Jack Dancoe