Hyundai Car 1999-05

Voltage Regulator



  1. Before servicing the vehicle, refer to the Precautions Section.
  3. Prior to the test, check the following items and correct if necessary.

    Check that the battery installed on the vehicle is fully charged.
    Check the alternator drive belt tension.
    Turn ignition switch to "OFF".
    Disconnect the battery ground cable.
    Connect a digital voltmeter between the "B" terminal of the alternator and ground by connecting the positive (+) lead of the voltmeter to the "B" terminal of the alternator and connecting the negative (-) lead to good ground or the negative (-) battery terminal.
    Disconnect the alternator output wire from the alternator "B" terminal.
    Connect a DC ammeter (0 to 150A) in series between the "B" terminal and the disconnected output wire.
    Connect the negative (-) lead wire of the ammeter to the disconnected output wire.
    Attach the engine tachometer and connect the battery ground cable.  

    Click image to see an enlarged view

    Fig. Diagram of connected Voltmeter and Ammeter


  5. Turn on the ignition switch and check to see that the voltmeter is properly installed and indicates the following value:
  7. Voltage reading = Battery voltage of 12.0 to 14.1 volts.
  9. If it reads zero volts (0V), there is an open circuit in the wiring between the alternator "B" terminal and the battery and the battery negative (-) terminal, or the fusible link is blown.
  11. Start the engine keeping all lights and accessories off.
  13. Run the engine at a speed of about 2,500 rpm and read the voltmeter when the alternator output current drops to 10A or less.
  15. If the voltmeter reading agrees with the value listed in the Regulating Voltage Table below, the voltage regulator is functioning correctly.
  17. If the reading is other than the standard value, the voltage regulator or the alternator is faulty.

    Click image to see an enlarged view

    Fig. Regulating Voltage table

  19. Upon completion of the test, reduce the engine speed to idle, and turn off the ignition switch.
  21. Disconnect the battery ground cable.
  23. Remove the voltmeter and ammeter and the engine tachometer.
  25. Connect the alternator output wire to the alternator "B" terminal.
  27. Connect the battery ground cable.

Removal & Installation

The voltage regulator is an internal component of the alternator. In order to replace the voltage regulator, the entire alternator assembly must be replaced. Please see removal and installation of the alternator for the instructions.