How to Troubleshoot an Alternator Regulator
An alternator converts mechanical energy into the electrical current required by various devices in a vehicle. An alternator's regulator controls the amount of current the alternator produces. Car owners can easily determine whether an alternator regulator is functioning correctly with a voltmeter.
Things You'll Need:
- Voltmeter
- Turn the ignition switch to the off position, and lift the hood of the vehicle.
- Locate the alternator in the engine compartment. It will generally be toward the front of the compartment, although specific locations vary by model. The alternator typically has a cylindrical shape and is connected by a belt that is driven by the engine.
- Connect a voltmeter to the field terminal of the alternator regulator, according to the voltmeter's instructions. The field terminal has the thickest electrical wire attached to it.
- Measure the voltage on the field terminal. It should have a small voltage, ideally less than 0.1 volt.
- Position the voltmeter so that it is still connected to the field terminal but is not resting on any moving parts. This step may require an assistant to hold the voltmeter in the correct position.
- Start the vehicle's engine, and read the voltage from the field terminal while the engine is idling. The voltage should increase to at least 11.5 volts, assuming your vehicle has a 12-volt battery. A lower reading may mean the voltage regulator for your alternator is faulty. The voltage regulator does not typically have parts that can be serviced, so a faulty regulator usually must be replaced.