Preparing for the test
Before starting the test, please complete the checks listed below.
Check that the battery installed in the vehicle is fully charged. The procedure for checking the battery is provided in the Battery section.
Check the tension of the alternator drive belt.
Turn the ignition key to the "OFF" position.
Disconnect the wire from the (–) terminal of the battery.
Connect a digital voltmeter between the generator "S(L)" terminal and ground.
Connect the (+) lead of the voltmeter to the "S (L)" terminal of the generator, then the (-) lead of the voltmeter to a suitable "ground" (to the body) or to the (-) terminal of the battery.
Disconnect the standard wire from the generator terminal "B".
Connect an ammeter (DC, 0-100 A range) in series between the generator terminal "B" and the disconnected standard wire.
Connect the (–) wire of the ammeter to the disconnected standard wire.
Fig. 7.21. Voltage regulator test circuit
Connect the test tachometer according to the manufacturer's instructions. Connect the (–) wire to the battery terminal (Fig. 7.21).
Verification procedure
Turn the ignition switch to the "ON" position and check that the voltmeter reading matches the specified voltage value.
If the voltmeter shows 0 V, then either there is an open circuit between the "S (L)" terminal of the generator and the (+) terminal of the battery, or the fuse has burned out.
Start the engine. Turn off all lights and additional electrical equipment.
Set the engine speed to approximately 2500 min⁻¹. Read the voltmeter readings when the generator output current is 10 A or less.
Analysis of results
If the voltmeter readings correspond to the nominal values of the regulated voltage given in the table, then the voltage regulator is in good working order. If the voltmeter readings do not correspond to the range of nominal values, then either the voltage regulator or the generator is faulty.
After completing the check, gradually reduce the engine speed to idle speed, then turn the ignition switch to the "OFF" position.
Disconnect the wire from the (–) terminal of the battery.
Disconnect the ammeter, voltmeter and test tachometer.
Connect the standard wire to the "B" terminal of the generator.
Connect the wire to the (–) terminal of the battery.