The alternator relay is a small electrical relay switch unit.
It is usually located inside the engine compartment, bolted to the body near to the alternator.
The alternator relay controls the flow of electrical current between the alternator, battery and the starter motor. It also prevents any current returning to the alternator.
Problems associated with a faulty relay can be, low battery power, trouble starting the engine and low electrical power to lighting and accessories. An audible repetitive clicking sound can indicate a malfunctioning relay. Replacing this part with a alternator relay will ensure a compatible fit with the make and model of your vehicle.