all my lights work, except the tail lights

yes...well the 1/0awg black cable that attaches to ground has some corrosion at the point where it connects...you cannot see it but on a microscopic level the power stream is getting interrupted....with unreliable ground powered devices go crazy and malfunction....use a coarse wirebrush to clean up the spot where the lug bolts to and the lug itself...nice n' scratchy to get all the corrosion off...then put the bolt back and turn the key~

...also five years old is as old as these tin/antimony batteries will go...as they'll stop accepting a charge ten percent per year...after five will be broilin' your alternator trying to charge a battery that isn't accepting a charge...anymore~ GET a NEW battery~ life will be good then~

the chassis is not getting grounded properly~

Do you show power in the rear bulb sockets? are they grounded? do your bulbs have good tits? and are your sockets bad so when you try to put them in after checking,. they quit working? If you actually do not have power back there, you can take the lightswitch out of the dash, pull it to where you can see it good, and look for melting. Remove the switch from its connector and inspect the switch and connector for a melted wire that has too much resistance over heating it. If you find that, there are repair connectors that can replace the damage, them you test for circuit resistance. less than 1/2 ohm is good.

aftermarket can probably get prewired repair connectors and new design bulb sockets. if not dealers can get them aftermarket short and cheap, or motorcraft, beefed up and extended.

Where is this cable located

Whenever repairing an electrical issue start at the load itself and work back toward the power source. dissasemble carpeted area and side panels for access. The rear taillight panel has the harness going across. If by"cable located" you mean power distribution? source to power the taillights ? after suggesting fuses and power distribution center, your next step is disassemle the light harnesses and search for power and ground. Further info can be found on computer at the public library.

Reference manuals can sometimes be found donated by ford to the public library when they are out of use. It is also possible to order some of the manuals from dealer parts and through helm publications. I cannot say whether they would have the EVTM for your car, but that's who you can ask.

An EVTM is the troublershooter used to correct problems and find sorta where to start looking, and if it's wrong? try the other side, or the other end, or lie in the trunk and feel around till you get an idea. Usually the wires come from the drivers side and then go across to the other side.

This is why vehicle repair technicians have to have some time for access as well as diagnosis and also repair. You are just beginning to discover what they search for all day in a car, and have to search manuals and a library for the info, then someone just wants the answer, thats the way it gets. They need to put their time somewhere. Hope you find it fast.

We have a city library near me that you can get an answer by phone, the reference desk knows things the computer is still trying to display or offer you to click on. The librarians can walk down an aisle, pull the manual, look up a quickest answer, then offer for you to come read for yourself if you need indepth info.

Had to run a toggle switch to the hot wire from the battery only way I can get it to work. Wire has to run all the way from Battery to back tail lights.

Did this work I have the same thing going on now

I'm having problems with my taillights they wont come on do you know the reason