Alternator Voltage Regulator Replacement Cost Estimate

The symptoms of a failing voltage regulator are similar to those of a weak or dead battery or a bad alternator. To diagnose the voltage regulator, a technician will first rule out a dead battery by using a multimeter to check for correct resting voltage (12.6 volts), and possibly conducting a load test to make sure the battery is capable of delivering proper voltage under a load. If the battery is in good shape, the technician will start the vehicle and test the system for operating voltage. A car, truck, or SUV should run with voltage between 13.5-14.5 volts. The voltage regulator is designed to keep the voltage in this range. If the alternator is putting out too much or too little voltage, either the alternator or the voltage regulator is likely at fault.

In most cases, the voltage regulator (which is located inside the alternator housing) is replaced in conjunction with the alternator. It is possible to replace only the voltage regulator on some vehicles - usually by disassembling the alternator to gain access - but because the other alternator components can wear out over time also, the alternator is commonly replaced. Whether the alternator is to be replaced or only the voltage regulator, the alternator needs to be removed from the vehicle. In order to do this, a technician will need to locate the alternator and remove any components that are in the way. Depending on the vehicle make and model, this could be a significant amount of work; some vehicles have several components that block access to the alternator. In some cases, the vehicle will need to be raised and supported off the ground for underbody access. With the alternator accessible, the technician will remove the serpentine belt, alternator electrical connections, and mounting hardware, taking care not to damage the radiator and other nearby components. Once the alternator is out of the vehicle it can be disassembled (for replacement of the voltage regulator) or simply replaced.