Had my car serviced early August, charging system checked, battery was OK and alternator was charging OK. Car ran good for a week after the service and told to bring it back when the faults are present.
You know when you have that feeling something is not right, one thing I noticed was the throttle was not as fluid as it used to be, I kept getting the P0622 fault if I launched the car from a stand still and then the dreaded derate kicked in. On one of my runs the charge light started to flicker etc and I thought nothing of it until the alternator started to whine and I was far from where I needed to be, 2 miles from my destination the smell hit me from the alternator then dashboard lit up like a christmas tree, just about every electrical component shut down, steering, ABS. It was a tense moment as the steering is not light and the throttle was all over the show. By the time I parked the battery was dead, the car had been running off the alternator and would not even wind the window up. Disconnected the battery after I parked it just to be safe.
AA chap came out, put some power to the alternator and used his heat gun to check the temp on the alternator, the windings were getting hot hence the burning smell earlier. Towed the car to the dealer the next morning.
New Denso alternator fitted and a new Ford battery. I have not had any issues, the little gremlins have not surfaced.
As for the wire on the fuel filter housing it has been plugged back in, I forgot what it is for!
In hindsight I should have changed the alternator and battery when I had the car serviced, given the age it would have done no harm apart from my wallet and I would habe avoided the "drama" that unfolded. The risk of fire is something to consider as well.