No power at trailer plug for tail lights
 

03 model truck
Everything on the truck works and Everything works on the trailer but the tail lights-running lights. Its the truck not the trailer. I have tried two trailers and have the same problem and I have checked the 7 pin plug with a volt meter and get no power for the tail light circuit. Where do I start to find the problem? It doesn't look like there is a fuse? If the truck tail lights work does that mean that the problem is between the tail lights and the 7 pin plug?
Please help
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03 2500 4x4 nv4500
04.5 2500 4x4 48re

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Last edited by stealman1; Today at 09:23 PM.. Reason: add

There is a separate fuse for the trailers LT/RT/Tail..look at the map under the fuse box cover for them...

The only ones that I saw that looked like they could be trailer tail light was 32,33,34 I think and they look good. Is the 7 pin wired from the truck tail lights?

I believe the whole trailer plug is separate circuits.Check the tail light blade in the plug it may be loose.This happened with mine but it was the left turn blade.New plug and all is good.

Check the harness and make sure it was not tapped into for a bed harness then remove the harness from the plug behind the harness and check the circuit there, like Matt says it could be a defective plug.. if you have no power there then your Power Distribution Center located under the fuse box is probably blown..I think these are in the 400-500 range or you can install one of these for about $50:

http://www.etrailer.com/Wiring/Tow-Ready/119190.html

Thanks for the ideas.

So is the 7 pin plug plugged into another plug that then leads to the power dist. center? And I can just unplug it behind the bumper? If so, how do I identify the running light circuit at that plug.

The link that you posted for the modulite thing has a straight four pin connector, how is it used to power the 7 pin?

The plug on the bumper plugs into the main harness (the truck lights and trailer lights are on a different circuit). pull the red tab and it comes off.. I don't have the color code for the plug with the Tails on one should be hot.

The modulite will get its signal from the trucks TS and Tail circuits (you'll have to tap in at the rear lights). The modulite has a separate wire that gos to the battery(for load power) and the flat four you see will have to be tied back into the main harness.. Look on the RH side of the link there is a PDF file for installation instructions download it and read it..

There should be a diagram on the plug cover.I found my problem with a test light.Wiggle the blades--if the tail marker is loose thats probably your problem.

You can unplug it at the back insert new plug and plug it back in.You can get the right plug at valley trailer.

Thanks for the help guys. I have a better understanding about the trailer lights wiring now. I looked over everything again and upon further inspection found that fuse 33 was blown. Its all good now.

I guess your buying beer and pizza for the DTR break room tonight [laugh]

Glad you got by cheap..

Hey, wheres the pizza and beer. My patience is running out