Checking the alternator
The charge control lamp indicates the failure of the alternator, included in the excitation circuit
In the event of damage to the excitation diodes or positive diodes, the battery is overcharged or undercharged, which is signaled by the control lamp glowing. In the same way, the control lamp informs about the defect of the negative diodes, which causes the alternator to discharge the battery. Another cause of the control lamp getting infected is the voltage drop in the cables or loosening of the terminals in the ignition switch or on the battery.
The illumination of the charge control lamp with the ignition switched off indicates a short circuit in the positive diodes, which then lead in both directions. The battery discharges when the engine is stopped.
To check the alternator, disconnect the three-pin plug at the voltage regulator, start the engine and attach tester tips to terminals "D + ” i „B + ” alternator. If the lamp of the tester dims together with the charge control lamp, this fault exists in the alternator. Conversely, if the probe bulb remains dark, and only the indicator lamp lights up, this damage should be found in the cables.
Alternator showing symptoms of malfunction should be removed and checked and repaired in a specialist workshop.