Attention. Do not apply battery positive voltage to alternator terminal D, otherwise it may damage internal components (power transistor) generator.
Checking the Charging System Indicator
1. Make sure the battery is fully charged.
2. Check the condition of the alternator drive belt.
3. Turn on the ignition (engine off) and check that the charging system indicator lights up. If the charging system indicator does not light up, but the wiring is normal, check the condition of the engine control unit.
4. Verify that the charging system indicator goes out after starting the engine. If the charging system indicator stays on, check for trouble codes and then troubleshoot.
Alternator voltage test
1. Make sure the battery is fully charged.
2. Check the condition of the alternator drive belt.
3. Turn off the ignition and disconnect all power consumers.
4. Start the engine.
5. Make sure that the generator rotates smoothly without extraneous noise when the engine is running. In the presence of extraneous noise, determine their cause and repair or replace the generator.
6. Using a tester, measure the voltage at each pin of the connector. If the measured value is out of specification, determine the cause and repair or replace the defective parts.
Note:
Generator Standard Voltage (ignition on):
- Conclusion B: B+
- P terminal: about 1 V or less
- Pin D: approx. 0 V
Generator Standard Voltage (idling, at a temperature of 20°C):
- Output V: 13-15V
- Conclusion P: about 3-8 V
- Conclusion D: turn on electrical consumers (headlights, blower motor, rear window heating, brake lights, etc.) and make sure that the voltage value has increased.
Checking the generator current
Note: Since the charging current drops sharply after starting the engine, perform the following procedure quickly and read the maximum current value.
1. Make sure the battery is fully charged.
2. Check the condition of the alternator drive belt.
3. Disconnect the negative battery terminal.
4. Connect a tester with a measuring range of at least 120 A between the alternator B terminal and the wiring.
5. Connect the negative battery terminal.
6. Turn off all power consumers.
7. Start the engine.
8. Vehicles without i-stop: Increase engine speed to 2,500 rpm.
Note:
- If the electrical load in the vehicle's on-board network is low, the required current cannot be checked even with a normal alternator. In this case, it is necessary to increase the electrical load (leave the headlights on for a long time to drain the battery, or use a similar method) and check again.
- If the generator or ambient temperature is too high, the required current cannot be checked either. In this case, it is necessary to allow the generator to cool down and repeat the test.
9. When the electrical load is on (headlights, fan motor, rear window heating, brake lights, etc.) make sure to increase the current. If the current does not increase, check the engine control unit and alternator using the M-MDS diagnostic tool (see the instruction manual for the device).
Note: The minimum value of the generator current (vehicles without i-stop system): 70% of rated output current (rated output current: 100 A) (ambient temperature 20°C, voltage 13.0-15.0 V, engine and generator warm).