We earn commissions from purchases you make using links in our articles. Learn more. The alternator is a device that keeps your car’s electrical system running once the engine is on. It’s essentially ...

Disconnecting the battery while the engine is running isn't a valid test for alternator function and may damage sensitive electronic parts. Instead, use a common voltmeter and the following test ...

Signs of impending alternator failure often include a slight reduction in the voltage reading on the dash, or noticeably duller headlights. It’s hard to predict unless you periodically do an output ...