First, you need to check all the generator's power supply connections. Check that the V-belt is properly tensioned. Further testing is possible with the generator installed; it can be carried out if an ammeter and voltmeter are available.
Connect the ammeter in accordance with Figure 243 between the cable and terminal "B" of the brushless generator. Turn on all lights and apply the brake pedal. Start the engine and check that the measurement readings are 70 A or more at an engine speed of 2500-3000 rpm.
Figure 243. Checking the AC brushless generator. The ammeter must be connected to terminal "B" (1).
Turn off all lights and release the brake pedal. The reading should now be 5 A or more at the same engine speed.
Connect the voltmeter according to Figure 244 between the terminal "S" of the plug box and the housing. The engine should run at 2500-3000 rpm. Check that the voltmeter reads 14.1-14.7 V. All lights should be off. Do not apply the brake pedal.
Figure 244. Generator voltage control. 1. Terminal "L"; 2. Terminal "S"
Turn on the ignition switch and check. so that the voltage between the "L" terminal and the body is within 1-5 V. If this does not happen, install a voltmeter between the "S" terminal and the body. With the current collectors off and the brake pedal not working, battery voltage should be shown.
Further testing is carried out with the brushless generator removed, but first you can still check whether all the fuses are in order. The brushless alternator must be replaced or repaired in a specialized workshop.