i have a 91 mr2 3sgte and its not charging at all.
i put in a second hand alternator and its still doing the same thing - no charge at all.
 
i tested the 3 wires coming from the harness and each of them had battery voltage except for 1. it only had 2.6v
Could the no charge issue be because one wire has less voltage than the others ? if so where do these wires lead to??
 
 
 
thanks!!
 

Check the (I think) 7.5 fuse in the engine bay fuse box

My alternator problem was worn brushes. Before I changed them, tapping the alternator with a hammer would temporarily fix it, but changing out the brushes cost $15 and my boy (16yrs at the time) got the alternator out and put the new brushes in. No problem since.