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Trailer Battery Charge Circuit

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Old 08-09-2007, 04:39 PM
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Trailer Battery Charge Circuit

All,
My 2007 Expedition has the stock hitch and 4 pin connection (not the optional tow package). I want to upgrade to a 7 pin connector, and add a trailer battery charge wire. There is a spot for a trailer battery charge relay (#56) and a 30A trailer charge fuse (#13) under the hood. Question: Where is the connection point to tie in to the existing harness, if one exists, to extend a 12v charge wire to the new 7 pin connector (pin 4 I believe). If a harness connector does not exist, what is the best way to make use of the existing trailer battery charge relay and fuse? The main fuse/relay block under the hood does not seem user friendly to hook into, thus I am hoping there is a dead-ended wire leading from it somewhere. (If the answer is somewhere in this forum already, I apologize.)
Thanks!
 
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Old 08-10-2007, 06:21 PM
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I think you'll find that the relay socket and fuse socket do not have all of the female electrical sockets installed which means there is no harness to connect to. I seem to recall that when I plugged in my tow relay that where there were missing fuses and connectors for options that I do not have like heated mirrors & power liftgate.
 
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Old 08-10-2007, 10:53 PM
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Your reply got me thinking 07EXPYEL. I got out the voltmeter to see if the pins in the fuse and relay sockets had any voltage on them. What I found was that all the relay pins were dead, but there is 12v on one of the fuse #13 pins. So I plugged in a fuse and found that 12v was now on one of the relay pins. I'd guess that's the 12v battery supply to the input side of the relay. Then I turned on the engine and found 12v was now on another of the relay pins, very likely one of the relay coil connections. I also found the relay coil ground connection. So now the question remains, is there a wire connection to the relay output pin, running somewhere, for a battery charge connection pigtail? If so, where the heck does that wire go? It doesn't go to the hitch area as far as I can see, so where else?? Thanks!
 
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Old 08-13-2007, 12:33 PM
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Thumbs up Trailer Battery Charging Solved

Thought I post the solution to my original problem; maybe it will help another Fordster. My 2007 Expy came with a 4-pin flat trailer connector. To upgrade to a 7-pin connecter and add a 5th wire to charge my Jayco pop-up trailer battery, I added a trailer battery charge relay (#56) and a 30A trailer charge fuse (#13) to the main fuse/relay box under the hood. Next, I found the orange wire that comes out of main fuse/relay box; It is going to a large connector near the master break cylinder. Use a tester to ensure you have the right Orange wire before connecting to it (it's right on top of the bundle of wires, next to a yellow wire). Then I ran a 20 foot length of #10 AWG stranded wire, with a protective sleeve over it, all the way to the new 7-pin tow connector. Now my trailer battery is charged with the protection of the fuse and relay that is part of the optional tow package from Ford. If you want more info or photos of the aforementioned connector, just let me know.
 
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Old 07-02-2008, 01:17 PM
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Trailer battery charge circuit

Here is what I found.
under the hood find the fuse and relay box, validate that you have the relays for trailer back up lights and trailer battery charge. I had the fuse but not the relays. your owners manual should show the location of each of these. why they are not installed with the tow package is odd. cost me $30.00. no wires to run. everything works. note that there are fuse for these as well I had the fuse but, not the relays. hope this helps.
 
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Old 07-02-2008, 03:40 PM
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My relays came with my truck, they were in the jack well in a sealed bag with instructions. I have the same problem of not being able to figure out where the output is. I was thinking about just getting a solar trickle charger for my trailer battery, its for an electric jack, so not too much juice.
 
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Old 07-09-2008, 10:04 AM
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nfntruth,

do yo have the 7 pin plug (factory) installed? on the the cover of the plug there is a wiring lay out. as you look at the cover the top righthand pin location is the +/ hot side.
check to to see if you get a reading from this pin (note that you need the key to the truck in the on position not assy) I just got back from the 4th vacation everything on my trailer and truck work perfect 1975 airstream 2002 crew 4x4 f150.

I did find that my trailer was not wired correctly had to switch the backup lights and the power side to match the truck.

Sounds like your almost there!

I'll look for this bag.
 
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Old 07-10-2008, 03:40 PM
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I have the factory 7 pin. I took a look at it and there didn't seem to be an extra spot, but I will look again. I may still go with the solar charger anyway, its a cool gadget, and the trailer doesn't get used more than once a month or so.
I wouldn't definitely check for he bag and complain to the dealer if it isn't there. Both my 06 Explorer and Expy came with it. I am positive its part of the tow package.
 
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Old 07-11-2008, 06:01 AM
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There should be a bag with the relay, fuse, and a schematic of the wiring.

These are all LINKS:


Relay (black):

Fuse (green):

Diagram:

Schematic:

-- Chuck
 
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Old 07-23-2008, 07:59 PM
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Originally Posted by nfntruth
My relays came with my truck, they were in the jack well in a sealed bag with instructions. I have the same problem of not being able to figure out where the output is. I was thinking about just getting a solar trickle charger for my trailer battery, its for an electric jack, so not too much juice.
My RV dealer said it should have been in the glove box (It wasn't). I called my Ford dealer and the parts guy didn't have a clue as to what I was talking about so I went to the dealer after work and got the sales manager involved. I went back to the parts section and he was about to order me the harness (he couldn't find anything else (the relay) so I went to Advance auto parts and he sugggested I Google "trailer towing battery charge coil" ( Since my rv dealer said it went into the passenger side fuze panel (WRONG). He was also wrong about where it should be found (JACK STORAGE just like it says here.) Soooooooooooooo I should be good to go when I plug the relay and fuze provided in the proper place (under the hood)
 
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Old 12-24-2008, 12:11 AM
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If you have the relay and wire in the jack area (as I do), does that mean your vehicle has the towing package upgrade or is this included in all Expeditions? I bought an 08 EL EB since I'm not the original owner I do not know if it has this feature?
 
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Old 06-18-2009, 09:05 AM
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Great thread we just bought a travel trailer and I realized that the charge wire wasn't heated up this saved me talking to the stealership gotta love FTE
 
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Old 06-18-2009, 08:34 PM
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Have any of you guys bought an EVTM for your expys? I usually purchase one from HELMS (online), and have one for every other vehicle I have owned. The description from Helms is a little ambiguous and "aint" exactly cheep, but I would buy it. I think you could find a wrg diagram on-line, but I like to have one in my fat little fingers, much more convienient.

I could go back to "search", have seen this answer before, but I am curious if there are any differences between the "tow package" and the regular (4 pin connector) other than larger tranny cooler (do-able) and a higher rated receiver (also do-able). Mine is a class three. I think I have seen that the non-tow pkg is rated considerably lower than the tow-package. Maybe thats because of the lower rating of the class III receiver. I also hope that the charge relay is the only connection between the tow vehicle and trailer, that the batteries are isolated when key is off. I dont know if the 7 pin has a 12V hot connection other than the charge ckt.
 
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Old 06-24-2009, 06:50 AM
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It's more than the receiver.

The Expedition HD Tow Package includes the full 7-pole wiring (the brake wire is connected not just loose), larger transmission AND engine coolant radiators, and a Class 4 receiver under the back of the truck. There are no mechanical changes. Same differentials, etc.

There's a complete auxillary fuse/relay box under the hood. See my two-year old photos linked previously and compare to yours.

Both radiators are standard parts and can be retrofitted. Engine coolant stays right about 197°F on mine. Towing or not, but our trailer is roughly 5000 pounds and the sysem is rated to 9000. $350 buys a lot of towing peace of mind.

-- Chuck
 
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Old 06-24-2009, 11:22 AM
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Chuck---I checked your old posts for the link, and was reminded that I had read most of them before----lots of good towing info. Having towed TT's before, I am not greatly worried about any of it, it is what it is. Really interested about the OBD2 data scanner. I wonder if the 6 speed has the thermistor in the tranny solenoid pack like the old E4OD. If so, the oil temp may not register as the hottest oil from the tranny. Oil in the pan is after the radiator and external coolers have cooled it down. My preference would be to put a sensor in the output lines to the coolers, which would be the hottest----at least I would think so.

Without looking (in a minute I will) I suppose the door sticker reflects the platform ratings, and hopefully not the "as equipted", that way, deputy "fife" would not see any problems if HD coolers were added. instead of OEM. You know how deputy Barney is-------
 


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