Make sure that the deflection and tension of the alternator belt correspond to the nominal values.
Disconnect the wire from the negative terminal of the battery.
Install an ammeter between terminal B and terminal.
Connect the wire to the negative terminal of the battery.
Turn off all electrical consumers.
Start the engine and set the crankshaft speed - 2000–2500 min-1.
Measure the current at the generator output. Measurements are made on «hot» engine at an air temperature of 20°C and a voltage at the terminals of 13.5 V.
Current strength:
- at 1000 min–1 - 0–75 A;
- at 2000 min–1 - 0–98 A.
Switch on the following electrical consumers one after the other:
- headlights;
- heater fan motor;
- rear window heater.
Verify that the current at terminal B of the alternator gradually increases. If the current does not increase, repair or replace the alternator.