Comment. If the battery warning light on the instrument panel does not come on when the ignition is turned on, there is most likely an open circuit from the instrument panel to the alternator (see «Checking and repairing electrical circuits») or the brushes of the regulator relay are worn out more than the permissible value (see «Voltage regulator and brush assembly - replacement»).
To perform the work, you will need a multimeter and a technical stethoscope.
We work with an assistant.
Execution sequence
1. We prepare the car for work (see «Preparing the car for maintenance and repair»).
2. We start the engine. If the control lamp of the battery charge is on on the instrument panel, check the tension of the alternator drive belt (see «Accessory drive belt - condition check and replacement»).
Recommendation. Weak tension of the alternator drive belt leads to its slipping along the pulleys, which does not allow the generator to develop the necessary power and leads to rapid belt wear. Indirectly, belt slippage can be determined by the dim glow of the headlights at night and by the whistling sound in the front of the car when the crankshaft speed increases.
3. Warm up the engine to operating temperature.
4. We turn on all powerful consumers of electricity (heated rear window, maximum air conditioner fan speed, high beam headlights, etc).
Comment. We carry out further operations with an assistant.
5. By pressing the gas pedal, we keep the engine speed within 3000-3500 min-1 and control the operation of the engine on the tachometer.
6. We measure the voltage at the battery terminals with a voltmeter. If the generator is working, the voltmeter should show a voltage of at least 13 V.
Comment. If the voltage is less than 13 V, the wire contacts from the generator to the battery may have oxidized, the voltage regulator is faulty, the brushes are oily or worn, or the generator itself is faulty.
7. We turn off all consumers of electricity, while the voltmeter should show a voltage not higher than 14.7 V.
Comment. If the voltage is greater than 14.7 V, the voltage regulator is most likely faulty.
8. With a stethoscope, we evaluate the condition of the generator bearings by noise. A strong hum indicates wear on the bearing or bearings (most often the front bearing fails).
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