Go to www.searspartsdirect.com Enter your model number in the appropriate box, when the page loads, look on the left side of the page where it says "Browse sub-components" and click on "tractor-schematic" this will open to a total wiring diagram for you
7way- black is 12volt (power), brown, running lights, yellow is left turn signal and stop light, green is right turn signal and stop light, white is ground, blue is brakes, and orange is aux power (can be back up lights, if trailer equipped w/ them). 6way is the same, minus orange wire. I have run into some variations to the above color codes (brown, yellow and green only-sometimes these 3 are different than stated, but only mixed as that group, as to what they control- example would be green is running lights, brown and yellow are turn signal and stop lights, the others should be as stated), if you have any trouble with things not working properly, it may be due to these variations, although the above are pretty standard. If you have an ohm meter you can check as you go (check for power at black wire- should be constant 12v, turn on turn signal and check for power-it will fluctuate from approx. 12 volts to 0 volts as the signal power pulses in the wire) hit the brakes, blue wire should show power, etc. Let me know if you need more help as you go.
The best solution is to use a Vehicle Specific Wiring Kit, as these cars have complex electronics that do not like being overloaded, Also the car has towing specific safety systems (such at Trailer Stability Program) which only work if it knows it is towing. The car will need to be coded to recognise the towbar wiring and work the saftey systems properly after the kit has been installed. It's not cheap however, Expect to pay around £200-£250 for the whole job.
Ford sells a wiring diagram book, really detailed, about $35
You should probably start with the manufacturer or an authorized dealer:
Northwood Contact Us
can you check with parts department at ford and see if thy can
otherwisw check with autozone