The circuit looks pretty straight forward. The alternator is connected to chassis ground and there should be a 2 wire connector. One wire should be a heavy wire going to the + power lead on the starter motor. (This is then tied to the battery + terminal) The other wire goes to the instrument panel and will cause the battery charge warning light to come on if the alternator output is lower than 12V. Is the light staying on? What is the output of the alternator at the alternator and at the battery when the engine is running? (Should be over 13 volts typically...) Fuse F30 in the cabin main fuse box looks to supply the instrument panel lights (including the charge light) but shouldn't affect the charging. There is a removable voltage regulator/brush assembly on the alternator that could be a problem. It could have a pin or clip holding the brushes which would need to be removed for operation.
Hope some of this helps...
