- the battery must be fully charged;
- all consumers, except the battery and ignition system, must be disconnected;
- the engine speed should be 2500-3000 min⁻¹. Measure the voltage at the battery terminals with a voltmeter. If the voltage does not exceed 14.5 V, the regulator is working properly. If it is higher, connect the regulator body to the car body with a separate conductor and measure the voltage again.
If in the second case the voltage is again increased, then the regulator is faulty and needs to be adjusted or replaced. If the voltage is normal, then the reasons for the battery overcharging are a poor connection of the regulator body to the "ground".
A faulty voltage regulator can be determined by checking its internal parts.
The reasons for the regulator malfunction may be the following:
1. Open circuit in temperature-compensating resistor 2 (fig. 7-11) or the regulator winding, while the voltage is not regulated and increases excessively. This malfunction can be detected by checking the electrical resistance between the "15" plug and the "ground" with an ohmmeter (basis).
2. Break in the choke winding or in the additional resistor 4; however, the regulation is unstable (sharp voltage fluctuations).
The malfunction is detected by checking the electrical resistance between plugs "15" and "67" with open contacts of both the 1st and 2nd stages.
3. Contamination, burning or oxidation of the contacts of the 1st and 2nd stages when the regulated voltage is unstable.
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The malfunction may be caused by the penetration of foreign substances into the regulator: oil, gasoline, water, which contaminate the contacts, or a short circuit in the wire circuit of the plug "67" or in the excitation winding of the generator. Penetration of foreign substances into the regulator occurs due to improper installation or damage to the sealing gasket between the cover and the base of the regulator, as well as if the gasket is made of an inappropriate material and does not provide reliable tightness or releases volatile substances.
If the contacts are damaged, it is recommended to check the condition of the circuits (short circuits and correct wiring connections), as well as the serviceability of the generator.