Summary; 02-05 Explorer Trailer Wiring | Ford Explorer Forums - Serious Explorations

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Summary; 02-05 Explorer Trailer Wiring

Summary 02-05 Explorer Trailer Wiring

I have continued to learn about the topic -- adapting 02 and newer Explorers for 7-pin trailer wiring. Much of what I have learned came from this forem by searching old posts. To help the next person who comes along, I now share what I have learned.

The 02 to 05 Explorers are pre-wired for 7-pin trailer wiring. I assume 06 and 07 probably are as well.

The stock 02 -05 Explorer comes with a 1.25 inch class 2 reciever hitch. It is easy to install a 2 inch, class 3 reciever hitch. Good looking after market units are availible from on-line retailers for just over $100. They bolt right on. This gives the added benifit of now having both types on your rig. One can for instance, tow a trailer with the class 3 reciever and have a bike rack mounted on the class 2 at the same time.

The stock 02-05 Explorer comes with a 4-pin trailer wiring plug. If you follow that wire to just under the passenger side tailight, you see a connector there. From this connector on, the Explorer is fully 7-wire trailer ready. So, just get the correct harness and plug it in -- presto, 7-pin ready. The harness is Ford part number 3C5Z13A576BA. MSRP for that is $123.68. However, it can be purchased for less finding on-line discount Ford part dealers. I found one for about $86.00 plus shipping. But to me, that is too much. I am searching junk yards for a wrecked unit that has the 7-pin harness. If I don't find one, I will use a 4-pin to 7-pin adapter from Wallmart ($25). It plugs into the 4-pin connector then has 3 other wires I will need to splice in and one ground connection to bolt to chassis ground. This would give me both 4-pin and 7-pin connectors at the rear of my trailer, which is nice. I already pulled the plug loose from under my taillight. The connector slides off the little plastic thing. Or you can pull the little plastic thing off the mounts by prying with a big screw driver. It's held on with 2 of those plastic-ribbed screw like things, and if you are not too rough, you will be able to put it back in place with no damage. The connector has a little slot on one side where you stick a screw driver to get it open, but be carefull. What you have to do is get your screw driver under a little metal spring clip in that slot. Then the connector comes apart pretty easily. Look in the slot that invites a screw driver with a bright light and you will see the little metal clip.

Fuses and relays: There is a fuse box in the engine compartment. And there is a relay box behind the passenger side plastic trim pannel in your cargo area. Open the tailgate. Look to the right. That big plastic pannel hides this relay box. The relay box is actually just in front of the tailight. The good news is, I think all the fuses and relays are already there on all units. My 03 has the fuses in place under the hood. I looked at the relay box in a junkyard unit -- 02 Explorer stock with no tow package, just the class 2 stuff that comes standard. The trim pannel was already pulled loose. It looks to me like the relays are already there. I'll report back on this thread if I find that is not the case. The bad news is, if we have to install the relays, then it seems like one has to pull the plastic pannel part way out, which is a bit tricky to do without braking it if one does not know the tricks -- which I do not... Maybe if the right rear tailight is removed, then the relay box will come out for access easily. If needed, I will try that. But I am optimistic (hopefull) that the relays are already in place.

Electric trailer brake controler: Again, the 02-05 Explorers are already pre-wired! There is a connector behind the glovebox. To get at it, one needs to drop the glove box down. This is easy to do, just open the glove box and then press in on the sides of the compartment -- you know, the place that holds stuff. You will see that there are like 2 pins on the sides. Just press enough that these pins clear the dashboard and the glove box will open all the way and hang down. Now you can see some wiring and connectors. Look around in there, you will find an unused connector. This is the electric brake connector. On mine, it was taped to a wire bundle on the left and towards the rear, close to the firewall. Electric brake controllers do not automatically match to this connector, but on e-trailer.com for example, they sell the pig-tail harness with the connector that plugs into this one for $10. On that web sight, when you find electric brake controllers, the wiring adapters are linked easy to find.

From e-trailer.com I ordered a class 3 reciver hitch, $119. A Tekonsha powertrack electronic brake controller. $59.95. And the adapter for the brake controller to fit the Explorer OEM wiring, $10.00. Shipping was 0.99.

Unfortunately, that 7-pin harness on the back seems only a Ford item, and I am not finding one in a wrecking yard. So, its the $25.00 Walmart item and a little splicing. If I don't post here again, it means the fuses and relays are all present. Otherwise, I'll report that.

OK -- Ive done my work here. Hope whoever needs this information finds it usefull!
 



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My experience with my 06

With my 06 its a bit different than described. If you follow from the 4pin up to just behind the passenger tail light you do indeed find a large connector that would appear to be where you connect a 7 pin harness. However, this is deffinately not the case with the 06. I just picked up the Ford harness to convert my 06 to a factory 7 pin harness. The entire harness is about 15 feet long, and has around 7 or 8 connectors on it. This harness powers both rear tail lights, the 4/7 pin trailer connector, then there are 2 small connectors that connect by the rear passenger wheel, and one or two more large connector(s) that seem to go above the fuel tank (approx under passenger seat). Lastly it connects to the existing harness just behind the front passenger wheel.

One important thing to note about this is if you choose to splice the cheap connector to the factory 4 pin harness is that there does not appear to be a wire to charge the on-board trailer battery in that harness. If you want that function (and you should, in case the trailer comes unhitched the battery powers the electric brakes), you will still need to run a power wire. I noticed that the new harness I have has a power wire in it, but my existing harness did not. This can easily be seen when looking at the existing harness behind the front wheel .

So, the only thing I see as a pain so far are the 2 connectors that I need to undo and redo that are above the fuel tank. I will have to remove the running board to get a better view of this. I hope I do not have to lower the tank.

I had to purchase the pigtail for the controller, but its very straight forward. It appears that the stoplight switch is wired into that harness so you do not have to make a splice for the stoplight microswitch that the brake controller makes reference to.

Lastly, this 7 pin harness does not include the actual 7 pin plug. It is terminated with a Ford connector that must then go to what I assume is another Ford part # which is the standard 7 pin receptacle. I am likely going to remove the 7 pin connector that came on the harness and will just connect the wires to a 7 pin plug (which I got for $2.88 at Princess Auto).

Again, its more or less straight forward except for the two plugs that I can not see. I will attempt this switch tomorrow (Wednesday). I will let everyone know what I find out.

James
 






Well, I attempted this conversion.. Don't bother. Unless you are willing to tie wrap the new harness to the frame. Even then there is a MUCH simpler way that looks like a factory job. Its impossible to get the old harness removed as it is fastened to the frame every 8 inches and for about 3 or 4 feet, it is fastened to the top of the frame (ie between the body and the frmae) and is impossible to remove. Not to mention you would have to remove the fuel tank to make that one connection..

I will be running one red wire for battery power from the main connector of that harness (located just behind the passenger front wheel) to the 7 pin connector at the rear. I will also cut the 4 pin connector off and reconnect the wires to the new 7 pin connector. You will notice that there is an unused blue wire under the rear bumper by the 4 pin connector. That is the brake wire and is the same blue wire in the pigtail for the brake controller. I also plan on tying a heavier ground wire to the frame for the added current of the electric brakes. 7th wire (middle pin) I'm not using. Not really sure what its for anyway. It says auxillary ground...

I will take some pictures of the install if anyone ever needs to see how its done, or where to grab the 12V power for the battery.

James
 






Dusting off this relatively old thread...

Any one have picture of where to grab the 12V power for the tow vehicle battery? He grabbed it behind the passenger wheel.
 












I have a 2005 XLT with the towing package. I previously towed a horse trailer with a Chevy and did not have any trouble with the factory wired trailer brakes on the trailer. The trailer uses the same 7pin so I thoought I could pull it with the explorer. It would not move the trailr brakes was activated. I thought they had froze up. Come to find out I had to disconnect the wire for the trailer brakes in the trailer side because I wasn't sure which one was the trailer brake wire on the explorer. Please help. All other lights etc work fine. What wire should I connect for the trailer brake.
 






Can someone please tell me what each wire does at the trailer connection on my 02 explorer. It has a 4 pin plug & I need to wire up my trailer lights.
 






My new, used 06 Explorer came with a class III hitch and standard round 7-pin connector installed at the factory. It looks like the L&R turn, tail and battery are wired and working.

Is the Aux. cable routed and fused? I can't seem to find any information on it.

I assume there is a plug somewhere that's all setup for a controller but I didn't see anything looking under the dash or glove box area. Must be there somewhere.


My manual has a glued over page from the factor that shows a fuse in location 25 that is rated to 15A for the trailer brakes. That's about all the info they have on the trailer wiring. Now if you want to know how to use the radio , there's 13 pages for that.
 






Just have one question about accessing the relay panel. How do you get the molding out of the back. I have a 05 XLT and in the cargo area it has molding all the way around.
 






Hi GCH, I have an 02 4.0 XLT that didn't come with the tow package and I have pretty much done everything you have to do to have the tow package installed. After reading article about the wiring, I went and had a quick look for the connector behind the passenger tail light. It was there. I found the fuses were in place for the electric brakes in the main fuse panel under the hood but I'll be damned if I can find the connector for the electric brakes in behind the glove box.

What does this connector look like? I have an empty connector underneath my sterring column and if I remember it was grey in colour. Any pictures would help.
 






Many thanks to GCH's post of 2007. I just followed his instructions EXACTLY and the change from 4 wire to 7 wire with installation of Prodigy II brake controller using factory wiring went EXACTLY as he described. GCH should look into a career as technical writer if he is not already one. Thanks again to GCH and those who want to tow trailers with your Explorer--his instructions work. (Assuming you already have the Class II hitch tow package.)
 






Ford Part number 3c5z13a576ba

I have the 4pin setup also. I have already plugged in my Brake controller to the connector in the glovebox. Now all I have left to do it unplug the 4pin just under the passenger tail light, and install the 7pin wire harness. I can not find this harness anywhere. Does anyone have any idea where I can get this harness?
 






4 pin and 7 pin update

My 2005 explorer has only 4 pin
It does have the connection in the glove box for brake controller.
I cut the tape off of the 4 pin about 4 inches back from the actual connector and guess what the blue line is already in there, they just cut it shorter from the factory and wrap it up with the other 4 wires.

So all I should have to do is:
Plug my brake controller into the glove box connector. Then buy a 7pin to 4 pin adapter and mount it on the bumper. Then plug the 4pin from the adapter to the factory 4 pin. Then I will splice the blue (brake) wire from the 7 pin adapter to the blue that is already wrapped in with the factory 4pin.

I should then only have to mount the white ground wire from the 7 pin adapter, and then run only 1 (black) line to the engine for 12v hot.

I have two question...
1. Does this sound right?
2. where do I get the 4pin to 7pin adapter?
 






i have an 04 has the 4 pin connector and i plug my trailer lights into it, and it don't work even cleaned them out still nothing at first wouldn't fit but i cut off some rubber around the ground plug on the trailer to fit it, nothing, do i need a special plug from ford to make it work?
 






I have a 2002 Explorer Ltd, and my wiring harness used to work fine. But now it only gives me running lights. No brakes, no signals. Mine may be an aftermarket install, I'm not sure. It LOOKS nice and factory though. It's a CLass II hitch, with an aftermarket air brake hookup.

I didn't check the fuses that are inside the cab on the passenger side, but the other fuses checked out. Maybe it's a fuse?

How can I troubleshoot this to know whether it's the hitch plug, which looks like this: http://www.rockauto.com/catalog/moreinfo.php?pk=2546970. The video indicates that many times they fail because of corrosion, which mine does show signs of. My hitch plug looks like that except I don't have the extra side mounted 4-pin adapter, which is slick. I have to use an adapter.

But is it the plug, or the wiring (Which is in flex tubing and disappears into the chassis somewhere). This indicates for vehicles with wiring already:

http://www.rockauto.com/catalog/moreinfo.php?pk=45121

Mine looks like that inside. With blade like connectors. I'm not sure how many... 6 or 7. I'd have to look. I'd have to guess that the wire from the fuse boxes to the rear of the veh would have to really LONG. Therefore, i'm guessing that at some point there is an interface somewhere that a part like this would connect to? But where would it be located, if using something like this? It would have to be mid chassis somewhere I'd say.


I don't want a wild goose chase, cuz I'm not sure what the heck I'm doing when it comes to wiring. But it USED to work just fine, then didn't. My jack looks a bit corroded too.

thanks!
Jason
 






I have a 2003 Explorer Limited with a 4.6L, which has the 2" hitch and the factory 7 wire plug.

I have checked and the 7 wire plug works with all the lights on my trailer.

I ordered the Tekonsha-Trailer-Brake-Control-Harness 3035-P to use my Tekonsha prodigy brake controller.

I found the plug behind the glove box to plug the 3035-P into.

Do I need to make any other connections to get the trailer brakes working?
 






I have just one question: where do I pass the controller pigtail to get from the driver side to the factory plug on the passenger side? There doesn't seem to be a passage big enough to push the pigtail through.

:dunno:
 






I have just one question: where do I pass the controller pigtail to get from the driver side to the factory plug on the passenger side? There doesn't seem to be a passage big enough to push the pigtail through.

:dunno:

I was able to shove it between the firewall, but it was tight.
 



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How did you ram it through?
 






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