I have an 02 supercrew without the towing package. It has a four pin plug but I want to add a 7 pin trailer plug. The trailer brake controller is wired to a Ford adaptor which does fit a plug under the dashboard.
The problem is where is the wire for the trailer brakes terminated?
Any ideas?
Thanks,

 

Go to a dealer and get the replacement harness that has both the 4 and 7 pin hardware.
At the rear area, there is a plug to replace the existing harness with the new.
You also need a relay and fuse to install in the right socket in the distribution box under the hood, with the changeover.
If you are going to pull a substancial load get an aux trans cooler in place.

 

The advice on the transcooler is spot on. However, you can add a 7 pin harness to any truck. You already have the brake lights and turnsignals already there in your 4 pin harness. You can rewire these to your 7 pin plug that you can pick up nearly anywhere. Walmart, pepboys, advance auto, etc etc had them. They are about $15 bucks.

Get a fuse holder and a roll of wire. I use 10gauge wire for my trailer brakes when I installed a brake controller on my 86 F150. The instructions will probably say to run a ground and hot to the battery. Fuse as close to the battery as humanly possible. You can take two wires and place them in a drill chuck. Hold firm, activate the drill and the wires will wrap into a nice good looking spiral.

Wire your trailer brake controller to the battery (fused) and tap the brake light switch as directed. Then run a power wire to the appropriate pin for the trailer harness.

The factory 7 pin does have reverse lights and aux power leads. It is up to you if you want to add this. I actually have a chepo set of driving lights on the back of my trailer to aid with backing and I really like it.

Depending of your comprehension of electrical stuff depends on what you can add.

The trailer brake controller will come with generic instructions that can be used as I described.

 

Go this route, else you are note going to have use of the pig tail under the dash. The manual wire in, will have you wiring part of it to the pigtail, and part to the home grown harness as suggested above. Not worth the trouble.

Check the tow section sticky thread on trailer tow relay locations, I thin kthis has the harness P/N for your MY ( I put in the 04-06 P/N's ).

Also a good idea, take a look at Troyer Perf, they have ( had ? ) a nice stacked plate cooler, with the fan mounted to it already. Nice piece of gear, and you can get all the required hoses, etc in one package ( at least you could, I did not look to see if Mike still had this on the web site ).

If the '04 Heritage P/N is the still the same as the 99-03 ( that is the old body style truck ) www.fordaccessoriesstore.com lists this as YL3Z-13A576-GB with a MSRP of $45.47.
I would think this is the correct one, with it being the old body style, but a check around the Tow section, or ask your delaer or the online part manager if you go that route, to confirm this, is in order.

 

I guess it depends on your skill level, availability of parts, cost of dealership parts, proximity to the dealership, etc. I did it on the 86 and it wasnt any trouble for me, however I have that sort of background. I would hapily do it again. The plug in harness is nice and to give all of the power options of the factory setup would be a few more steps.

Anyway now anyone that reads this has an idea of a couple of options.

 

In the "old" days, one could do all sorts of shade tree wiring and get away with it. (1986 would qualify as the old days.) By the way, some folks were much better at this than others. With the newer trucks - and I would call that anything after the late 1990's - you can really make a big mess in a short period of time with this type of wiring. In my humble opinion, the days of the "Scotch Lock Hacker" are long gone - and for good reason. One of the big reasons Ford added the "Upfitter Switch Panel" option to the Super Duty line of trucks was that so many warranty problems were actually caused by folks adding electrical accessories the wrong way and burning stuff up. Just my 2 cents.

 

I did the DIY brake controller and harness ( along with the HD flasher ) on my 81 F-100 and 90 Dakota, as there was not other option.

It was not hard at all, just dirty work running running the 10 AWG wire front to rear, adding in the relay off the reversing circuit to power a seperate lead for the trailer reversing lead, and installing the HD flasher.

Skill level aside, why get that dirty for the sake of saving 30.00 was my reasoning. The fuses are already in the fuse panel in the correct location, so anyone can find them, not in water proof fuse holders under the hood, seperate reversing circuit already installed, no need to tap into the factory reverse lights to add this, etc.

Take the material and time to DIY it, vs spending the 45.00, and how much easier / cheaper is it ?

BTW : safety wire in a drill is ok, stranded wire, for power, in a drill is a no - no. Use Linemans pilars for that, same results, and no chance of breaking strands in the wire.

 

Its done every day in the Telecom industry where five nines of reliability is expected. Five Nines mean that a piece of equipment is up for 99.999% of the time.

I am probably at the point as well that I'd spend the $30 and just plug and play. It is worth the price IMO as well. I didnt realize it was so reasonably priced.

 

Where are they splicing 10 AWG together ?
Usually straight runs from the rect to the fuse panel in the bay, then to the gear.

Never seen a MOP cover putting a splice in a power run anywhere....

 

This thread has played out the whole range of time and experience.
I too wired an 85 and even built a insolation relay assembly for trailer use that was all signal relayed to the trailer. Worked like gem as long as I had the truck.
I too am retired from the telcom industy.
The new trucks are not worth the hassle that could result by home 'remidies' unless you know what you are doing. Coming to a board after problems, is difficult to get help with because often the discriptions don't match the actions taken and we don't have crystal ***** to be able to see this.
I did install on my 02, a backup circuit triggered relay and it's own power thru a fused #10 to hi powered backup lights. There are side marker/turn signals added thru their own relays for turn signal use as well as marker use. Extra Fogs with switching relay control.
For those who are not so comfortable with electric circuits, get the factory harness, plug it up and make it easy for yourself.
My trailer controller is a Prodigy that just plugs up to the plug under the dash.
The trans coolers are two in lines and a hi capacity cast alum pan with temp gages in the output line just off the trans and one in the pan for full monitoring research. There is a lot to cooling that is never realized or known about. I could write a small book on it already and still not have all the info that can be known.
The rig pulls nearly 12,000 lbs gross combined weight going into the second summer.

 

Not for splicing but for twisting cables with a drill. Wasnt that what we were talking about? That is the only way I have ever seen it done. Lucent, Alcatel, Comverse, Tellabs I have seen all of these installers use the same technique at one time or another. As a technique to run cables down the frame to keep them neat. From the fuse panel at the top of the rack to the equipment wherever.

Funny thing is that for the last 10 years I have worked in a sector of Telecom called wireless. But I tell you in those 10 years I have done more with wires than I ever did the whole remainder of my life.

 

Post #3 above, talking about 10 AWG trailer wire.

When I am at the "C" company tomorrow morning, I'll see if ask them if they do this.
Got me, I have seen it done for safety wire by a mechanic, but not on a frame.

I still dress down with a Kansas City stich to the cable brackets on the rear of the frame.
When turning down out of the ladder rack, and joining to another run already in place, I use a Modified Chicago Stich.