- multimeter (in voltmeter mode with a measurement range of 15-20 V);
- technical stethoscope.
1. Prepare the car for work (see "Preparing the car for maintenance and repair").
2. Start the engine. If the battery charge indicator light on the instrument panel lights up, then check:
- serviceability of fuse F16 (see "Mounting block replacing relays and fuses");
- supply of +12 V voltage to the generator excitation winding when the ignition is turned on (connector D);
- alternator drive belt tension.
Recommendation: Weak generator drive belt tension (see below "Generator Drive Belt - Checking Condition and Adjusting Tension") causes it to slip on the pulleys, which prevents the generator from developing the required power and leads to rapid wear of the belt. Belt slippage can be indirectly determined by the dim glow of the headlights at night and by the whistling sound in the front of the engine when the crankshaft speed increases.
3. Warm up the engine to operating temperature (at least 80°C).
4. Turn on all powerful consumers of electrical energy in the car (heated rear window, electric heater fan, high beam headlights, heated seats).
Note: We perform the rest of the work with an assistant.
5. By pressing the gas pedal and monitoring the engine operation using the tachometer, we maintain the engine crankshaft speed within 3000-3500 rpm.
6. Using a voltmeter, measure the voltage at the terminals of the battery. If the generator is in good working order, the voltmeter should show a voltage of at least 13 V.
Note: If the voltage is less than 13 V, the alternator drive belt may be loose (see above), the alternator circuit may be faulty, the alternator voltage regulator may be faulty, the alternator brushes may be oily or worn out, or the alternator itself may be faulty (troubleshooting of the voltage regulator and other generator components, see below in the relevant sections).
7. Turn off all electrical consumers, while the voltmeter should show a voltage no higher than 14.7 V.
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Note: If the voltage is greater than 14.7V, the voltage regulator is most likely faulty.
8. Using a stethoscope, we evaluate the condition of the generator bearings by the noise. A loud hum indicates wear of the bearing or bearings (the front bearing fails most often).