Hi. I am getting ready to tow a small utility trailer and want to install a trailer light harness so the trailer will have tail and brake lights. It there a plug and play kit, like through E Trailer or Curt that someone has used? Or do I just need to splice in a Blade harness? Any help is appreciated.

2004 Ford Edge Ranger 3.0L 2X4

bryan

 

In 2004 the factory trailer harness is wired through the SJB. If its not factory installed, taping into the tail light harness is the easiest way.

 

Yes their is a plug and play harness, i bought mine from summit racing. My truck had nothing so i purchased it. It plugs in on each side right at the tail light in between the bulb connector and the truck wire harness connector and has enough wire to run down to the middle where the trailer hitch reciever is. Its the 4 pin blade type. I believe it was only !5$. I then bought the kit that converts from that to the round plug and came with all the stuff to wire a brake controler. But for some reason my trailer lights dont work, i havent done any trouble shooting yet. The brake controler works the trailer brakes but no lights what so ever.

 

One of the main failures in trailer lights is the Ground.

DC power needs a full circuit, voltage must "flow" from positive terminal of the battery to the negative terminal of the battery to complete the circuit.
(there is evidence that it actually flows from - to + but same thing still applies, lol)
12volt wire is only 12volts IF there is a 0volt wire(Ground)

If the trailer is smaller then you should run a Ground wire from EACH light to the tongue, along with the Tail/brake power wires.
And make sure truck Ground used for connector is the SAME one used by the trucks tail/brake lights.

If trailer is larger then use the trailers frame as the ground.
Make sure tongue ground is BARE METAL, for ground connection, then you can paint over it or seal it.
And each light has the same BARE METAL ground

And I would fuse the 12v trailer wires, most newer vehicles with factory trailer wiring have extra fuses in the cab fuse box/SJB just for the trailer wires.
Adding 2 or 3 inline 5amp fuses won't break the bank, and losing trailer light because of a short is not great but without the extra fuses you will also lose trucks tail/brake lights

 

Take a closer look along the frame rail on the drivers side, somewhere along the center line of the spare. You will probably find a connector about the size of you small finger taped back to the wiring pigtail. Use the factory harness if at all possible as it is an isolated feed from the truck lights.

Another clue is to look in the fuse box. Check you owners manual for the trailer fuses locations and relay location. If they are there or at least have connection on both sides of the slot then you are wired for trailer feed. You can get the 'adapter' or just splice in your own. The factory adapter merely makes the transition from the ford round connector to the flat four pin.

The advantage of the trailer circuit is that if you have a short it only pops the trailer light circuit, your truck lights are isolated. If you tow a number of different trailer you can stop at NAPA and get re-settable breaker to go in place of the fuses. Did that on my F150 and was grateful many times for the resetting breakers instead of fuses.

 

I can't thank you guys enough in how much the information you supplied solved my issues. Actually it was a combination of almost every response, so having each and everyone of you to provided feedback to get me up, running, safe and legal!

Thanks!!

bryan

 

Good work

Thanks for the update

 

I just puffed the wiring to my brakes and all with a flat four prong plug in unit. The box fried while the shop was trying to see why my entire lighting from the dash back went out. The turn signal switch , which apparently controls a lot of stuff was swapped out for new, bringing back the tail lights, turn signals and four way flashers, but weak and still no brake lights. While trying to see what was going on, the trailer hook up box fried itself. They yanked it out and reconnected the harnes and everything was back. Seems some of the boxes on the plug and play harnesses aren't so good.

So now I want a round pin style plug to have a better hook up that may be a bit more impervious to crappy weather. Either a 5, 6 or 7 prong, whatever it takes. Any suggestions on what one is the best? I am willing to pay what it takes to get the best so I don't get fried again. If this means FoMoCo and a C note no problem. So tell me, what is best. No more flat four or five for me.

 

Splicing into existing truck wiring is an accident waiting to happen, but........thats what trailer light wiring is, even if it is Factory Trailer wiring.

Color codes found here: How to wire up the lights & brakes for your vehicle & trailer

I have always used waterproof inline fuses at the trailer connector for Parking, Stop and Turn wires, backup lights are up to you, but inline fuses are cheap, lol.
Also use heat shrink on each connection

If your trucks Brake light fuse is 10amp then use a 5amp fuse at trailer connector, same for other lights, use lower amp fuse
If running a 12volt wire then fuse it at the battery end AND the trailer connector, same for electric brakes

Spend the time on the connections and they will last for years, but they WILL fail overtime thats just the nature of weather exposed wiring

 

Not sure what plug and play unit you are using, but MOST of the off the shelf units do NOT have a ground connector. That fourth pin is the Back UP, not Ground.

 

Wasn't spliced. It was one that plugged into the light harness under the left rear corner.

You are talking fuses in the wiring, can it be trailer side of the plug or is there a good reason to put it on hitch side? No problem with soldering and shrink wrap, not a firm believer in crimp ons, especially in the elements.

 

So, add a ground, trailer side of the plug okay, or should it be hitch side? Putting in additional fuses will make it easy to add the ground to the trailer frame, a bit more effort on the hitch.

 

Added fuses go on the truck(hitch) side of wiring, this prevents problems with the truck's lights if connector is shorted out, which is why you use the fuses, to keep truck lights working if there is a problem.

You can then use the truck to drive and get more fuses and parts to fix the problem, without getting a ticket for no rear lights, lol.

Yes, 99% of trailer light problems is the Ground, so make sure you have a good frame ground on hitch connector and on trailer connector

 

Thank you for the help. I will do that.

 

So, how are they grounded?

I have the harness again. wires are white/black, yellow/black, brown/black, blue/black Tekonsha 118325 T unit, no idea where to find an honest to gawd wiring diagram for it to see what is there.

Seems from what I've found, the white is ground. No backup lights. Plus brown may be green, I'm a bit color blind.

 

Wut... flat 4 wire harnesses the oddball pin is ground its white and always has been. Brown is always right next to the oddball terminal and is taillights, yellow is left/brake and is next to brown, green is right/brake and is farthest from the oddball pin.

that thing? i see plug n play and not sure why its not working for you.

the green wire may be appearing to blue to you. In that pic in the amazon link on the trailer plug the far left exposed pin is your ground (white), then its brown, yellow, then green - hope that helps with the color blindness thing.

Is your trailer wired correctly? that will fry those boxes if it gets power to places it wasnt supposed to go...