Saturday night, I was putting on my tailgate LED strip. When I plugged it up and tried it, everything worked except the running lights. Today I had to pull our backhoe to VA. I plugged in the trailer and turned on my head lights, no running lights on the trailer. I have a 6 pin round and a 4 pin flat connectors. I check both the 4 and the 6 with a volt meter, no running lights. I unplugged the pigtail from the factory connector(near the bumper), and checked everything with a volt meter. I don't have +12 for the running lights in the factory connector. All the lights on my truck work, and I don't have any blown fuses. Any ideas?
Thanks

 

There's a relay in that circuit to provide that current. Is it installed?

Pop

 

Are you SURE no blown fuses, they have them pretty "broke down" as far as a fuse for this and a fuse for that, they even have a seperate fuse for left and right trlr. turn signals. Make sure you find and check a fuse for Trlr. Run. Lmps. Should be fuse #4 in the PD box under the hood. prob. a 20A mini fuse!

 

I haven't saw a relay. Where should it be located?

I checked all the fuses, but I'll check them again when I get home this evening.(Seems like ya always miss 1 or 2)
Thanks

 

Though mine's a 2000, and yours is an early 1999, and there COULD be differences, here's where my trailer tow relay box is located. It's added on when the trailer tow package is installed.



Something we haven't asked: Have your trailer lights EVER worked with this combination truck/trailer? Is this the first time you've towed this, or another, trailer with this truck?

Pop

 

Here's a good place to look.

 

I'm somewhat confused by what you've originally written in your first post.

Can you clarify?

Pop

 

Pop,
I am not 100% sure that is correct about the relays. The 2 relays on my truck are for the reverse and the 12V charge for the trailer. They were not in my truck before I hooked up the 7 way RV plug and there was a 6 way plug and a 4 flat on the truck when I got it. There was also 2 fuses for the fuse box next to the relay box that I had to install. I would think it could just be a fuse.

 

I remember missing some voltages when I first put in my trailer wiring a couple of years ago. I use the factory kit. You may be right about what signals were missing, but I remember having to install the relays in the box (came without) to activate them.

I also remember that the engine has to be running to get any voltage on the "battery charge" pin. That gave me a bit of trouble until I realized it.

I'd get into my wiring diagrams if my CD reader were working right now. :-((

You're likely completely correct about what the relays in the auxiliary box are used for.

Edit: Ahhh, just looked. Relays 38 & 39! Your are correct!

Still, there's this nagging recollection of a running lamp relay for the trailer.

Looking for my hard copies of a partial diagram I used on another project. Seems there was shown that relay on one of the pages.

Pop

 

Thats the right info. I just installed those two relays this past weekend. Double check the fuses in the box under the hood. When I first got the truck I couldnt understand why the left turn signal worked and the right didnt. Everything seems to have individual fuses. IIRC, the relay for the trailer parking lights (along with turn signal flasher and another relay) is behind the dash board right about where the 4x4 floor shifter is.

 

From '99 owners manual


Power Distribution box
#4 20A* Trailer Tow Backup Lamps, Trailer Tow
Park Lamps

#8 15A* Trailer Tow Electronic Brake Illumination,
Park Lamps, Trailer Tow Park Lamp Relay


http://www.motorcraftservice.com/pub.../99f23og4e.pdf

 

Ok.....on the 2001 models, the relay for the trailer running lamps is located on the I/P block under the dash. The large relay is for the turn signal flasher, one smaller one is for the fuel pump, and the other is for the trailer running lamps. The 99's may be different though. The easiest way to get to this is through the trash bag hook thing or take the lower part of the dash off below the a/c controls. Hope it helps...I'm off to work.

 

Thanks to all of yall. Got it working. It was fuse #4. I guess I just missed it when I checked the 1st time.
Thanks

 

Resurrecting this one:

What is the name of that relay box? I'm trying to wire mine right now, have put all the fuses in, but the "trailer tow backup lamp relay" [#38] and the "trailer tow battery charge relay" [#39] aren't available without that box (I assume this, not actually HAVING the box to verify).

I have been googling for a bit, but am not coming up with the proper description for that added-on box that'll enable me to have a functional trailer...

Any help would be GREATLY appreciated.

 

Okay, I found it. It's the "Trailer Tow Relay Block Harness" # F81Z-14A346-A.

I googled this part and came up with jack squat. Any ideas?