Final answer:
During a full-field test of an alternator, the voltage regulator temporarily ceases to function as it is bypassed to test the alternator’s maximum output.
Step-by-step explanation:
When an alternator is full-fielded, the component that temporarily ceases to function is the voltage regulator. A full-field test bypasses the voltage regulator to apply maximum current to the alternator’s field coil (rotor). This is done to test the maximum output capacity of the alternator. During this test, the voltage regulator is effectively taken out of the circuit, and thus, does not function temporarily. Once the full-field test is over, the voltage regulator is reconnected and resumes its normal operation, which is to regulate the voltage output of the alternator to a safe and consistent level suitable for the vehicle's electrical system.