Pontiac Firebird voltage overcharge issue with potential regulator or switch concern on Pontiac Firebird

Submitted by jridge · Jun 23, 2025
Published by RepairPal

Problem overview

Some Pontiac Firebird owners report experiencing voltage overcharge issues that may involve the regulator or switch, which can lead to the generator light remaining on and indicating a problem with the charging system. High resistance in the circuit can cause the voltage regulator to output excessive voltage, resulting in overcharging, making it essential to address such resistance issues promptly. Owners may find it helpful to test the voltage directly at the alternator or battery when problems arise, as erratic gauge behavior can indicate a need for further investigation, especially if the ignition system has been upgraded. While maintaining originality by using the old-style voltage regulator is advisable, those unconcerned with originality might consider replacing it with a new style alternator, ensuring the maximum voltage output remains around 14.8 volts. Proper adjustment of the voltage during the installation of the regulator cover is crucial, as is checking the wiring circuit to ensure the generator light functions correctly; a break in this circuit can prevent the alternator from activating and result in no charging output. In some models, if the alternator is a Delco with a model number ending in "SI," further troubleshooting may be necessary if replacing the alternator does not resolve the charging issue.

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