Ford no longer use the 3 wire smart alternator system .Current models use a 1 wire logic control but still a smart charge circuit.

Hi mate, did you ever get to the bottom of this problem? I've having exactly the same issue! Would be really grateful for an update on how you got on. Many thanks!

Same issue I have replaced the alternator had a new battery fitted.and had the smart charge wire replaced..and still the battery light comes on.any ideas ty

Fault fixed!!

Our 2012 Fiesta 1.25 has had an intermittent battery light fault for a couple of years. I hate intermittent faults - every time I checked the battery charging voltage it was OK. Finally this month the light stayed on during a longish trip and the battery went flat. The alternator was not showing any output. I changed it for a secondhand one and the problem has gone! I stripped the old alternator to see what had gone wrong after only 40k miles. I found copper strands in the brushes/ slip ring area, presumably peeled off the slip rings. I think they were occasionally shorting out the rings, then clearing off until the next time. The brushes were OK, although there was a wear slight groove on one slip ring. I fitted new brushes and cleaned the slip rings, so I have a spare on the shelf, just in case! You can check the brushes fairly easily - if you ignore the pain of removing the belt to get the alternator off. It might be possible to do it in situ, but there is not a lot of space down there.

I doubt this is the answer to most of the faults listed above, but may be worth checking. Good Luck!