I am having issues with my alternator not working. I have a 3g alternator with a 4 gauge wire running to the starter solenoid and the two black and orange wires capped off. The battery is a brand new optima and the alternator is brand new, but when I read voltage at the battery it is always reading under 12 volts even when the rpm is up. I run after market guages and read somewhere that the factory guage battery light had to be connected for the alternator to work. Is this true?