Does the alt. idiot light excite the alternator?

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As I understand it, if the alternator idiot light is burnt out, the alternator will not get excited and hence not work because the filament acts as hot wire to the alternator (the "exciting" part of its function).

Maybe I've crossed into old timer territory, because could this be true only in the days when generators were ubiquitous, but not in these modern times? I don't have a charging problem, but I do breathe a sigh of relief when the idiot light glows upon starting the motor.
 
Much depends on the vehicle and year and electrical system design.

Put a voltmeter across the battery with the engine running.

Anything over about 13.6 volts should tell you the alternator is generating current.

Many if not all modern alt. indicators are driven by the ECU, as well as the exciter current to the rotating field inside the alternator.
 
My late model 528 has a resistor in parallel with the bulb. Earlier 528s didn't have the resistor, and if you didn't see battery bulb with the key in run, the alternator wasn't charging
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