i hav a 2001 fiesta with a alternator/charging fault,had the alternator checked and it is ok on bench,i hav battery voltage to the bolt on termanal to the alternator and the other plug has two connections in it one is going to the battery warning light on dash if i earth the pin out the battery warning light on dash comes on but dont know what other wire does can anybody help please

 

It will be a 'Smart Charge' system, that 3 pin plug is part of it usually the problem is the wires can come loose in that connector, rarely it's a problem with the ECU itself.

Martin