Help Alternator Not Charging

[local_boy]

Hi, need a bit of tech help. Our yaris (1.0 GS Y reg, french built) Has decided to stop charging the Battery. Killed the original Battery which has been replaced

Pulling my hair about a bit, have checked all the feeds on the back of the alternator and at first glance seemed to be ok, it puts the charging light out on the dash but only manages to charge around 12.2-12.8V, not the 13-15V it should be. First thought was alternator which was replaced - no joy having had time to re-check wiring all seems normal except the wire to the ECU, seems to have 10V from somewhere which seems a bit odd.

Just wondering if:

1. Anyones had a similar problem?

2. If someone can pop the plug off on their yaris and tell me what figures i should be getting to each wire with the ignition on (Yellow, Black/red and blue wires to earth)