Also check with a tester for voltage at the large alternator connector. It should always be here - if it is not there, then check the connection of the generator to the battery. If the voltage regulator on your car is located separately from the alternator, then it may also be faulty. In this case, it is better to remove the alternator and voltage regulator and contact an auto electrician.
The simplest test of the generator load current is as follows: turn on the side lights of the car and start the engine. If the lights do not start to burn brighter when the engine is running, then this is the best evidence that the generator is not producing current. If you have a voltmeter, connect it to the battery terminals and start the engine. At high idle, the alternator should be producing current, and the voltmeter should show about 14 V. Does the reading differ by more than 1 V? Either the alternator or the voltage regulator is faulty.
In many cases, the constant burning of the control light indicates a malfunction of the generator, but malfunctions are possible elsewhere, and the generator, paradoxically, at this time may be in good order.
And yet, for most car owners, the control light is the only indicator of the health of the generator. The most common causes of abnormal functioning of the charge indicator lamp and typical situations are shown in the table. For example, the line "The control lamp does not light up" implies that the ignition must already be on, and at the same time it does not mean that the engine must be started. Generator malfunctions are listed in order of increasing probability of their occurrence. Faults in italics are not directly related to the generator. Below is a table explaining what some of the above problems can lead to.
Typical malfunctions reflected by the charge control lamp
Pilot lamp | Cause |
Does not light up
| Loose brush contact |
Faulty voltage regulator | |
Defect in the rotor winding | |
Poor ground contact or lack thereof | |
Discharged battery | |
Faulty control lamp, fuse, switch, wiring | |
Does not go out
| Faulty rectifier unit |
Defect in the stator winding | |
Faulty connection with brushes | |
Worn bearing (noise) | |
Defects in wiring, broken drive belt | |
Weakly lit when starting the engine
| Faulty rectifier unit |
Loose connection of the electrical wiring of the power supply circuit of the control lamps | |
Flashes when the engine is running
| Poor brush contact |
Faulty voltage regulator | |
Adjustment broken |
Generator | Cause |
Poor brush contact
| Brushes stuck (dirt), worn out. Contact rings are dirty. |
Rectifier failure
| Connections of terminals with conclusions of the battery "mass" wires are dirty or missing. Battery connection error (reverse polarity). Incorrect connection to the auxiliary battery at start engine. Electric welding was carried out with a connected generator. Lack of terminal contact in the generator connectors, contamination of the terminals or their corrosion. |
Bearing failure
| Most often occurs due to excessive tension of the drive belt. When the alternator pulley is loaded, the slipping belt makes a sharp noise a sound that does not mean that the belt is tight. Worn drive the belt rests on the bottom of the pulley groove, and not on the side walls of the pulley, which is produces this sound. |
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