Ok, so a little background.
2004 F150 XLT 4x4 5.4L

About 2 months ago I installed a set of Aux backup lights. I grounded them to the frame and tied directly into the backup lights in the rear tail lights. Worked great until Sunday

Plugged my trailer into the 7pin harness (if that makes a difference) and noticed the running lights on the trailer were not on. Figured something was wrong with the trailer so I figured I would fix it later.

Well when I got home and was backing the trailer in, we noticed none of the backup lights on my truck were working. I bought the dumb things to use while backing up the trailer and they didn't turn on.

Did the obvious tests. Checked the fuses by the pass. side kick panel. Tried 10 & 14. Both were good. Are there any other fuses related to this.

Asked SScully about it and he said there is a backup sensor on the trans that I may have fried. Does anyone have a picture of this? Also, how do I get to it if I want to test it? Is it accessible from under the truck?

Thanks in advance for any help.

 

There should be a towing fuse located under your hood. I believe it is located on the drivers side of the truck but I can't remember exactly. In your owners manual it should indicate the proper number of the fuse.

 

Most of those fuses are in the passenger's footwell. There is a seperate fuse for a lot of things to do with the trailer harness. I know my right signal on the trailer quit working because of a blown fuse.

 

It's not just the trailer. It's the stock backup lights that don't work on my truck. It's very difficult to backup without them. You'd be suprised.

 

Check Fuse: F10 (20amp fuse) and Fuse: F14 (10amp fuse) in the fuse panel behind the passenger floor kick panel. Otherwise it's a bad (DTR) Digital Transmission Range. I have a wiring diagram that will show you the complete circuit if you would like a copy send me your email.

 

Looks like two different issues;

First, the trailer tow harness has no power unless you install Relay 05 (C2110). Look for it in the main fuse panel; it is the middle relay in the lower row of relays. If it's not there, you won't get power to C439a, the 7-pin connector. Relay p/n is FOAZ14N089A, list $7.99.

Second, the reversing lamps are protected by two fuses, the first F2.14 1o Amp for power to the reversing lamp relay, and F2.10 20 Amp for the lights themselves. On the main fuse panel, find F2.14 being the 3rd one from the left in the vertical-mount fuses running just below the lower relays. For F2.10, it's the 2nd one up in the left column of horizontal-mount fuses running up the left side of the fuse panel.

I would say in your case, F2.10 is blown due to overload from your accessory reverse lights on top of the OEM lights. I added my reverse lights by running another heavy-gauge power wire from the fuse panel back, and using a relay in line with the reverse lamp circuit to activate the new lamps. You could also tap off the Orange w/ Green Stripe power wire (protected by 30 Amp fuse F2.106) in the trailer harness to power your new lamps, but the important thing is to use a relay in the reverse lamp circuit to activate, but not power, the aux lamps. BTW, the reverse lamp wires are Black w/ Pink Stripe.

Hope this helps. Let us know how you make out!

 

If you could email me that, it would be great. please email to berry.douglas@gmail.com


DONSFX - I had full lights before on the trailer. I have all the relays installed as I have used the trailer on several occasions before this. It was just the first time using the trailer with the new lights. Before posting I tried doing a search and realized I shouldn't have installed the lights like I did. Just too much of a draw, powerwise.

I have checked fuses 10 & 14, neither are blown. That is why I'm lost.

 

You got mail

 

Well, I always go for the obvious first. Sorry it didn't work.

The DTR is on the left side of the xmsn, the lowest connector aft of the bell housing.. From pin 11 of its connector, a Dark Green w/ Yellow stripe wire goes to the central junction box (main fuse/relay panel). In there, it energizes the coil of C2278 Trailer Tow Relay, Reversing Lamp (this powers both the normal "factory" reverse lights as well as the trailer's). In the panel, C2278 is Relay 301...it's a smaller relay that's the first one on the left of a row of 5 smaller relays between the upper and lower rows of large relays. Try swapping R301 on the far left with R305 on the far right of the same row (R305 is for the horn). That may be the problem. Also, while R301 is out, turn the key to "run", depress the brake and put it in 'reverse' (CHOCK THE WHEELS OR HAVE PARK BRAKE SET) and use a multimeter to measure volts from pin 2 (DTR) to pin 1 (Ground) and look for 12vdc...that'll prove if the DTR is working or not.

Other than that, I can't offer anything else. Hope it works out!

 

Thanks guys for all your help. I got the email Whitecrystal.

I'll figure it out. I'm hoping it's something easy, it's cold again this weekend and have to do this outside. errgh.

 

If you are talking about the relay that comes in the brake control wiring package, it only has to do with the trailer charge circuit. It doesnt affect the turn/run/brake lights on the 7 pin trailer plug.

doibugu2: When you fix your problem, make certain that you add a good fused power source and a properly rated relay. As I am sure that you have gathered, you cant just pile accessories onto factory circuits without some problems.
My wife's uncle was asking me about my reverse lights. He was impressed when I told him how I had hooked them up and the fact that I used a diode to prevent back feeding. He is a service manger for Land Rover and says that people often add lights and damage the vehicle because of overvurrent and backfeeding.

 

Well it was just a fuse. I was checking the wrong one. I guess I have problems counting to 10. I jumped right to 11.

Thanks for all the help from you guys.

I rewired them and ran the lights directly off the battery and installed an inline fuse. Installed a switch in the dash to turn them on and off. Would like to have them turn on and off with the brake lights, but isn't really necessary.

I didn't really think to much about adding the lights as far as drawing a lot of power. Just didn't think much at all.

Thanks all again.

 

I LOVE THIS SITE! lol

Came home and neighbor said "when you pulled out earlier you didn't have any reverse lights." Knowing how I baby my truck.

I thought

A quick search on here later, ran outside, pulled fuse 10, replaced the blown one, and right back on they came.

Thanks guys!

 

Just add a relay and a rectifier diode and you can have them come on with the switch and the the reverse lights. Thats what I did and I love the way it works. The factory lights do not come on with the switch, just the aux. The diode is a one-way valve. It keeps the voltage from feeding back into the factory harness.

 

be glad that they wouldn't come on rather than wouldnt come off. The ones on my 04 STX won't come off and I have had to yank the number 10 fuse 4 times and take my truck to get it fixed...hopefully this fourth time is a charm after every sensor has been replaced.