Trailer Lights work for ford and Gm but not dodge truck

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19er16417

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Apr 29, 2012
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I recently purchased a boat and trailer; the trailer needed new lights. Installed the lights by the diagram given and they were not working. I have a 2008 Dodege 1500 and everything else I have towed with it the trailer lights work. Have checked the fuses; have used voltage meter to make sure I had power to my tow hook ups and everything has checked out. Now for the weird part. The trailer lights work perfectly for a ford and Tahoe vehicles of a neighbors but I don't even get running lights to turn on when I hook up the Dodge.

please help,

Goin Crazy
 
H

H20Rat

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Re: Trailer Lights work for ford and Gm but not dodge truck

Grounds... I'm guessing your wiring harness gets its ground from the trailer hitch. Bad idea, but lots of OEM's seem to think this is a good idea. The dodge somehow isolates the hitch from ground, but it still has enough ground to show up on a voltmeter.
 
MH Hawker

MH Hawker

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Re: Trailer Lights work for ford and Gm but not dodge truck

Dose the dodge use one of the T connectors in the main harness to drop out for the trailer lights.
 
tomdinwv

tomdinwv

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Re: Trailer Lights work for ford and Gm but not dodge truck

Just traded in my 08 Dodge 1500. Are you using the 7 pin plug with an adapter or are you using the 4 wire plug under the bumper? I always used an adapter in the 7 pin and never had a problem. Smokincrater is probably right. A bad ground is the most common problem. You need to take a test light or multi meter and check the wiring on the truck side. Make sure you have power on each wire when your supposed to and make sure it is grounded good.
 
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19er16417

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Re: Trailer Lights work for ford and Gm but not dodge truck

I am using a, 7pin plug to 4 flat pin, adapter out of the Dodge. Another weird chapter to this story. We plugged the Dodge in to his construction trailer and the Dodge lit everything up. The boat trailer has decent rust on the hitch end. Would running a longer ground wire to some good metal be the way to go?
 
bajaunderground

bajaunderground

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Re: Trailer Lights work for ford and Gm but not dodge truck

I had a buddy tow my boat last summer to the lake for us in lieu of us taking 2 vehicles...he has a 2007 Ram 1500, had the same issues. Sounds as if that was the reason why?

Hmmm...
 
tomdinwv

tomdinwv

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Re: Trailer Lights work for ford and Gm but not dodge truck

Look under the bumper of your truck. There should be a 4 wire connector tucked up under there by the hitch. Try plugging into that and see if that works. If I remember right, there is a ground wire in the 7 pin connector. Check it with a volt meter set on Ohms and see if it shows good.
 
H

H20Rat

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Re: Trailer Lights work for ford and Gm but not dodge truck

19er16417 said:
I am using a, 7pin plug to 4 flat pin, adapter out of the Dodge. Another weird chapter to this story. We plugged the Dodge in to his construction trailer and the Dodge lit everything up.
Click to expand...

That trailer probably uses the ground in the hitch harness, vs grounding from the trailer frame/hitch.
 
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19er16417

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Re: Trailer Lights work for ford and Gm but not dodge truck

Thanks everyone for your help. We ended up running the ground wire back further on the trailer, bipassing the hitch and it lit up light a Christmas Tree.
 
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