Possible causes of generator malfunctions and ways to eliminate them are displayed in the table
- Cause of malfunction
Remedy
The control lamp does not light up when the ignition is turned on
Control devices not working
- F19 fuse blown in the mounting block
Replace the fuse
- Break in the power supply circuit of the instrument cluster:
Do the following:
- - no voltage is supplied from the mounting block to the instrument cluster;
- - check the "O" wire and its connections from the mounting block to the instrument cluster;
- - no voltage is supplied from the ignition switch to the mounting block
- - check the "GP" wire and its connections from the ignition switch to the mounting block
- - Ignition switch does not work
Check, replace the faulty contact part of the ignition switch
The control lamp does not light up when the ignition is turned on and does not light up when the engine is running
Control devices are working
Battery low
- The control lamp has burned out or the contacts of the lamp holder are not pressed tightly against the printed circuit board
Replace burned-out pilot lamp, bend lamp socket contacts or replace it
- Break in the circuit between the instrument cluster and the "D" plug of the generator
Check the "KB" wire and its connections from the alternator to the instrument cluster
- Wear or freezing of brushes, oxidation of slip rings
Replace the brush holder with brushes, wipe the rings with a cloth soaked in gasoline
- Damaged voltage regulator (open circuit between terminal "DF" and "ground")
Replace voltage regulator
- The wire is disconnected from the “D +” terminal of the brush holder
Connect the wire
- Short circuit in positive valves
Replace the rectifier
- Soldering the field winding leads from slip rings
Solder leads or replace alternator rotor
The control lamp lights up brightly or glows dimly when the engine is running
Battery low
- Alternator drive belt slip
Adjust belt tension
- Damaged voltage regulator
Replace voltage regulator
- Damaged rectifier valves
Replace the rectifier
- Power supply diodes of the excitation winding are damaged
Replace diodes or rectifier unit
- Soldering the field winding leads from slip rings
Solder leads or replace alternator rotor
- An open or short circuit in the stator winding, shorting it to ground
Replace generator stator
The control lamp lights up when the engine is running. The battery is being recharged
- Damaged voltage regulator (short circuit between terminal "DF" and "ground")
Replace voltage regulator
Increased generator noise
- Damaged generator bearings
Replace rear bearing or front bearing cap
- Interturn short circuit or short circuit to ground of the stator winding (generator howl)
Replace the stator
- Short circuit in one of the generator valves
Replace the rectifier
Checking the generator 9402.3701–04
We start the engine, let it run for a few minutes, and bring the engine speed to 3000 min -1.
We turn on all consumers: high beam headlights, tailgate glass heating, heater fan, etc.
We measure the voltage at the battery terminals with a voltmeter, which should be higher than 13.0 V.
If this is not the case, the voltage regulator, the generator windings are faulty, or the slip rings of the generator rotor are oxidized.
In order to make sure that the voltage regulator is working, turn off all consumers, except for the main beam of the headlights, and measure the voltage again.
It should be between 13.2-14.7 V.
To check the voltage regulator removed from the generator we connect a lamp (1–3 W, 12 V) to the brushes, and a DC power source to the brush holder terminals, first with a voltage of 12 V, and then 15 -16 V.
In the first case, the lamp should be on, in the second, it should not.
If the lamp is on in both cases - there is a breakdown in the regulator, if it is not on - there is an open or broken contact between the brushes and the voltage regulator terminals.
In both cases, the brush holder with regulator voltage needs to be replaced.
To check the rotor winding, you need to remove the brush holder with voltage regulator.
To check the short circuit of the rotor winding to ground, connect the tester probes (in ohmmeter mode) to the contact ring and the generator case.
The tester should show infinity, otherwise the winding is shorted to ground and the rotor needs to be replaced.
To check the breakage of the rotor winding connect the tester probes (in ohmmeter mode) to the slip rings.
If the tester shows infinity, then there is a break in the winding and the rotor must be replaced.
We examine the stator windings. There should be no signs of overheating on the winding insulation, which is the result of a short circuit in the valves of the rectifier unit.
If the windings show signs of overheating, the stator must be replaced.
To check the stator windings, you need to disconnect the winding leads from the rectifier unit.
To check for a break in the windings connect the tester probes (in ohmmeter mode) to the winding terminals.
If the tester shows infinity, then there is a break in the winding.
Similarly, we check the remaining windings.
To check the short circuit of the stator winding to ground we connect the tester probes (in ohmmeter mode) to the winding terminal and the generator case.
The tester should show infinity, otherwise the winding is shorted to ground.
Similarly, we check the remaining windings.
Checking the rectifier unit valves can be done on the car without removing the generator.
The "plus" of the tester (in ohmmeter mode) is connected to the B+ terminal of the generator, and the "minus" to its case.
The tester should show infinity. Otherwise, there is a short circuit in both the positive and negative valve banks.
To check the short circuit in the positive valves Connect the “plus” of the tester (in ohmmeter mode) to the B+ terminal of the generator, and the “minus” to the output of one of the stator phase windings.
The tester should show infinity. If the tester indicates the presence of a circuit, one or more positive valves are broken.
To check the short circuit in the negative valves Connect the “plus” of the tester (in ohmmeter mode) to the output of one of the phase windings of the stator, and the “minus” to the generator housing.
The tester should show infinity.
If the tester indicates the presence of a circuit, one or more negative valves are broken or the stator windings are shorted to ground.
