where the bulb wire attaches to the alternator (white wire, i think) earth it and see if light comes on. if it does its an alternator fault.
if it doesnt come on, check power and the bulb. Your Alternator will not work without there being power on that wire. that wire is the field/exciter wire.
1. The stator windings, this is a 3 phase machine, it has 3 sets of coils.
2. Main rectification diodes, sometimes referred to as the rectifier stack or pack.
3. Field diodes.
4. Field coil, the winding on the rotating shaft in the alternator, connected via the slip rings and carbon brushes to the regulator circuit.
5. Surge protection diode stops the output voltage rising above a predetermined safe level.
6. Dashboard warning lamp.
7. Ignition switch.
8. Battery, stores the charge provided by the alternator. It should be noted that the battery is always connected to the alternator though the main lead
9. To vehicle systems, usually distributed to the circuits via the vehicle's fuse box(es).