2004 Ford F-250 Auxiliary Charge Line Fuse for 7 Way Connector

Updated 01/02/2020 | Published 01/01/2020

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Question:

The interior lights on my new snowmobile trailer do not work. I suspect that I need the fuse, relay or both in my trucks fuse box responsible for these in order for them to work. I have not been able to find what locations in my fuse box these are for my 2004 Ford F250 anywhere online. Can you help, please. Thank you,

asked by: John F

Expert Reply:

I'll start by saying that how your trailer lights are powered depends on how the trailer is wired; in most cases the lights on your trailer are going to be powered the auxiliary battery on your trailer and not on a separate circuit. This battery is going to be charged by the 7 way connection between your truck and trailer.

I would start by verifying that your 7 way connector is providing power to all of the circuits; you can use a 7 way tester like the # PK12741 to test to make sure that power is being supplied to all of the pins on your 7 way connector. You can also test them individually using a circuit tester like the # PTW2992, to verify that each circuit is hot. If you find that your 12v auxiliary circuit is not providing power, there could be a blown fuse or the charge line could be completely damaged. You'll want to first replace any blown fuse, but I would also recommend checking the wire that runs from your battery to the 7 way to make sure it is not damaged. According to the owner's manual of your vehicle, the location of the fuse that powers the charge line can be found in slot 115 and will be a 20A maxi fuse. These fuses can be found in the fuse box that is located on the drivers side of the vehicle, in the cab.

You can also verify this by applying 12V power from a separate battery to this pin and seeing if that supplies power to your lights (see attached picture).

Assuming that the other lights on the trailer are functioning normally, it's most likely that these lights are powered via the battery and not via one of the light circuits.

If you replace this fuse and the wiring is in good condition, but your interior lights are still not functioning properly, please let me know and I will provide you with a few other things to have a look at.

expert reply by: Erik B