...... Having spent a couple of afternoons trying to track-down my electrical problems last week ->
Injector driver relay clicking - engine dies....
I've found it was All due to the connection block at the top of the, drivers side, inner wheel well. It makes the transition from the battery (+) to Fuseable links feeding the fuse panel (pictured below)
When plugging/unplugging the computer connector on the firewall I disturbed this wire, which is at the bottom layer of many wire looms, and it broke (probably for the best as it was easier to find over the intermittent connection it was
It seems that FORD, in their infinite wisdom, secured this block in place by bolting it through the well and then "keying" in with a slot & tab that leaves a hole to the spray the front tire makes when going through puddles. Here in the Northeast, this often contains a corrosive mix of salt & slush in the winter time which is now a 1/2inch from this block that contains the nickel (from the fuseable link), copper, tin, and steel (from the nut & bolt it's all fastened together with) along with the salt, and Galvanic action does the rest!
I don't know how many other trucks have this located here and are susceptible to my problem, but if I owned another truck like mine, I'd go take a look at it now
It's pretty easy to spot, a 1X1 black box labeled "CAUTION HIGH CURRENT" next to the airbox