Preparing for the test
Check that the battery installed in the vehicle is fully charged.
Check the tension of the alternator drive belt.
Turn the ignition key to the "OFF" position.
Disconnect the cable from the negative (–) battery terminal.
Connect a digital voltmeter between the generator "S(L)" terminal and ground.
First connect the (+) lead of the voltmeter to the "S (L)" terminal of the generator, then the (-) lead to a suitable "ground" (to the body) or to the negative (-) terminal of the battery.
Disconnect the standard wire from the generator terminal "B".
Fig. 7.12. Adjustable voltage test circuit
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. 7.12).
Connect the test tachometer according to the manufacturer's instructions. Connect the wire to the negative (–) terminal of the battery.
Verification procedure
Turn on the ignition and check that the voltmeter shows the specified voltage value (battery voltage).
If the voltmeter shows 0 V, then either there is an open circuit between the generator "S (L)" terminal and the positive (+) terminal of the battery, or the fuse has burned out.
Turn off all lights and additional electrical equipment. Start the engine.
Set the engine speed to 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 off the ignition.
Disconnect the cable from the negative (–) battery terminal.
Disconnect the ammeter, voltmeter and test tachometer.
Connect the standard wire to the "B" terminal of the generator.
Connect the cable to the negative (–) terminal of the battery.