Preparing for the test
1. Before testing, check the following items:
- the condition of the battery installed in the vehicle;
- alternator drive belt tension.
Warning! The battery used to test the current produced by the generator must be partially discharged. With a fully charged battery, the test cannot be performed due to insufficient load on the generator.
2. Turn on the ignition.
3. Disconnect the cable from the negative battery terminal.
4. Disconnect the wire from the "B" terminal of the generator.
5. Connect a 0-100A DC ammeter in series between the "B" terminal and the wire disconnected from the generator. Make sure to connect the negative probe of the ammeter to the wire disconnected from the generator.
Warning: Connect the wires and ammeter probes very securely, as a large current will flow through the circuit.
6. Connect a voltmeter (0-20V) between the alternator terminal "B" and ground. Make sure the positive probe of the voltmeter is connected to the alternator terminal "B".
7. Connect the tachometer and the wire to the negative terminal of the battery.
8. Leave the hood open.
Examination
1. Check that the voltmeter scale is clearly visible to determine the voltage value. If the voltmeter shows 0 V, then the electrical circuit connecting the generator terminal "B" and the negative terminal of the battery is not closed, the fuse link is burnt out, or the connection to the "ground" is unreliable.
2. Start the engine and turn on the headlights.
3. Turn on the high beam headlights and the heater fan to maximum air flow. Briefly increase the engine speed to 2,500 min⁻¹ and read the values on the instruments, while the ammeter will show the current produced by the generator.
Warning: After the engine starts, the battery charging current decreases very quickly, so this check must be performed very quickly.
Check result
1. The ammeter reading should be above the limit value. If the current value is less than the limit value and the wire connecting the generator output is OK, remove the generator from the car and check it.
Current Limit:
- 52.5A for 75A generator
- 63.0 A for 90 A generator
Warning! The current limit is indicated on the nameplate attached to the generator housing.
Warning! The current produced by the generator depends on the temperature and load. Therefore, to obtain the maximum current value, partially discharge the battery, first turning on the headlights of the car with the engine off.
Warning! The maximum current value produced by the generator cannot be obtained if the generator or ambient air temperature is too high.
2. After completing the generator current limit test, idle the engine and turn off the ignition.
3. Disconnect the cable from the negative battery terminal.
4. Remove the tachometer, voltmeter and ammeter.
5. Connect the wire to the "B" terminal of the generator.
6. Connect the cable to the negative terminal of the battery.