Its weird that the wht/blue wire has voltage, but does not turn on the battery light when you ground the wire. You may want to try a voltage drop test. You could also use a higher amperage test light then measure the voltage. Loading the circuit may cause a severe drop in voltage.

 

Actually, perhaps I mistyped.

There is hot voltage on white/green and black/yellow - no voltage on white/blue. The problem is just that it does not turn on the light when I ground it.

 

No voltage on wht/blu means that there is no power to that wire, so your charging light will not turn on. The bulb for the charging light is upstream of where you are testing, and that would be my next step. This will not solve your charging problem just your indication light.

If the wire you call black/yellow is actually blue/yellow, then the fuse upstream is ok, because it powers blue/yellow and the white/blue wires.

 

Ok, so I guess you were right.

After replacing the alternator again the charging voltage seems to be good. The battery light still does not work but I suppose that is a separate issue.

Thanks for trying to help...

 

The battery light is likely due to a bad bulb in the cluster. Replacing the bulb will likely fix the problem.