Trailer lights HELP

[Stressed11]

When I plug in my trailer the light come on, the trailer clearance and tail lights. They are on all the time even when the truck is off and engine is not running. If I leave it like this it will run the batt. down or I have to disconnect every time I stop. I've tried to find the wiring diagrams, for a 2004 F350, buy can't find one. Is this a wiring issue or possibly a relay? Where does the wiring from the back connect to the cab? Any help would be great.

Thanks

[jbawilliams]

It sounds to me like your trailer battery charge wire is crossed to the tail/marker lamp wire, and so the tail/markers are on when it is plugged in. There is a standard for wiring, but sometimes, a newly acquired trailer will not be wired correctly from the previous owner. To trouble shoot it, you need a 12V test lamp/probe, or an analog meter - the digital multimeters are to slow to respond. Be sure that the truck is wired properly, and then be sure that the trailer is wired correctly.


This might help:

Trailer Wiring


I don't know how to make it a link, but you can paste it into your browser.


Woops, I guess it is a link after it is posted.

[MrJohnWayne]

I would suspect a crossed wire like JBA or a wire with to much insolation missing causing it to contact a power source.

[Evil Eye]

with with they said.

[pipelayerjdh]

Make sure the trailer is grounded well, also.

[Stressed11]

I guess I should add the problem is in the truck, the trailer worked fine with my last truck, as well as with my brother-in-law's.

[pipelayerjdh]

What model truck do you have?

[Stressed11]

2004 F350 Crew Cab Long Box SWD 2WD

[pipelayerjdh]

Everything should be plug and play. Is the wiring factory? I would check the ground first. Grounding through the ball is not good enough. Make sure the white wire is attached to the frame. A bad ground will make the lights do crazy things. If that doesn't work, you'll have to try to tace the wires out. Determine which one is hot when not supposed to be with a test light, and trace it to the source.

[Stressed11]

Well I got tired of screwing with it, It was something in the dash. When I pulled the fuse, the trailer lights would go out so the wiring was ok from fuse to plug. So I just cut the wire on the 7way plug and hooked it to the truck tail lights. The way you would if you are putting in an after market plug. It tested ok and the lights on the trailer go off and on with the dash switch.