alternator?

Have you tried jump starting the vehicle? Is the battery OK? You need to have a good battery and a running engine to properly diagnose the charging system, so do that first before even thinking about replacing the alternator. This may best left to a shop, they can test this out in about a half hour.

First: check if the battery is OK if not change or charge second: get a muti tester check the voltage of the battery Note: Engine is Running. It should register 13.8 - 14 volts DC. if below the specified volts@ 13.8 there's something wrong on the alternator voltage regulator.( need to change). But in regards to your problem I think there something wrong on the starter motor/solenoid. or on the wiring itself./ fuses.