S Type charging light

My 2007 Diesel XS had the charging light come on whilst driving a few weeks ago. Next day it went out. Had a few things checked, fuses fault codes, etc.and decided to leave for a while to see what might happen. Have used the car a far bit and it has been OK but today, the charging light comes on for about 20 seconds and goes off for a few minutes then back on,off, etc…Charging at the battery with just engine on and no charging light on shows 14.3 volts, 12.6 volts with switched on everything on. Not been able to check volts with charging light on yet.
Any ideas? Any easy tests I can try?? Is the alternator on its way out, diodes, loose connection? Any help gratefully received.


Sounds like a classic case of the alternator brushes wearing out.