Unlikely. The supply from diode trio to field circuit is internal to alternator. There is no diode in the warning light itself or associated wiring.
Just to recap when all working correctly the diode trio and main alternator outputs should be at the same voltage (or very nearly so). This voltage to a degree is controlled by the battery and how much current it demands which in turn is controlled by the regulator adjusting the field current to control the output voltage. When the battery and loads combined drag the alternator output voltage down below its regulated limit around 14 volts (ideally 14.4v) the regulator will cause the alternator to run flat out commensurate with engine revs.
