Checking the Generator (GEN)

Checking the generator (GEN)

Checking the generator charge voltage

Note! The conditions for this test are that:
- The battery is fully charged
- The power supply and ground terminals for the generator (GEN), battery and starter motor are fault-free
- The belt transmission is fault free
- The L signal between the generator (GEN) regulator and the central electronic module (CEM) are fault-free and that no diagnostic trouble codes (DTCs) for the L-signal are stored in the central electronic module (CEM).

Warning! If the engine cooling fan (FC) is running, wait until it has stopped.




- Connect a voltmeter to generator (GEN) B+ and ground.

Hint: The appearance of the generator (GEN) face on D5252T engines differs from the illustration.

- Start the engine. Maintain a constant engine speed of approximately 2300 rpm
- Ensure that no additional power consuming components are connected.
Check that the system voltage in the battery and charge circuits is normal. For information about the charge voltage and temperature dependency, see Generator (GEN) / Charge regulator [1][2]Specifications.

Hint: If the generator (GEN) is not charging try tapping the generator / regulator lightly. The regulator brushes can stick and therefore not come into contact with the slip rings on the rotor.









Is the charging voltage OK?

OK - No Fault Found

HIGH - Replacing the component

LOW - Mechanically checking the regulator and generator (GEN)

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Replacing the component
If the voltage is too high it means that the regulator is defective. Try a new charging regulator.





Select "Continue" when the fault has been remedied.

Continue - Verification

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Mechanically checking the regulator and generator (GEN)




- Ignition off
- Remove the charge regulator from the generator (GEN).
Check the bushes. If the brushes are worn, replace the regulator. Check that the brushes can move in the regulator housing. The brushes are lightly sprung.
For information about the minimum length of brushes, see Generator (GEN) / Charge regulator [1][2]Specifications.

Check the resistance of the rotor winding of the generator. Use an ohmmeter directly on the slip rings. For information about the resistance values, see Generator (GEN) / Charge regulator [1][2]Specifications If the value is incorrect the generator (GEN) must be replaced.
Remedy as necessary.

Warning! If the engine cooling fan (FC) is running, wait until it has stopped.

- Reassemble the regulator, generator and terminals
- Connect a voltmeter to generator (GEN) B+ and ground
- Start the engine. Maintain a constant engine speed of approximately 2300 rpm
- Ensure that no additional power consuming components are connected.
Check that the system voltage in the battery and the charge circuits is now normal. For information about the charge voltage, see Generator (GEN) / Charge regulator [1][2]Specifications.
If the voltage is now normal it means that the regulator was temporarily jammed or there was temporarily play in the regulator.









Is the charging voltage OK?

Yes - Fault Found

No - Try a new charging regulator

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Try a new charging regulator

Note! There is an internal fault in the charge regulator or the generator (GEN) if the charge voltage is still incorrect. Try a new regulator.

Warning! If the engine cooling fan (FC) is running, wait until it has stopped.




- Reassemble the regulator, generator and terminals
- Connect a voltmeter to generator (GEN) B+ and ground
- Start the engine. Maintain a constant engine speed of approximately 2300 rpm
- Ensure that no additional power consuming components are connected.
Check that the system voltage in the battery and the charge circuits is now normal. For information about the charge voltage, see Generator (GEN) / Charge regulator [1][2]Specifications.
If the voltage is now normal it means that the regulator is defective.









Is the charge voltage now OK?

Yes - Fault Found

No - Replacing the component

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Replacing the component
The generator (GEN) is defective if the charge voltage is still incorrect and the new regulator has no effect. Try a new generator (GEN).

Select "Continue" when the fault has been remedied.

Continue - Verification

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Verification




Verification

Verification

Hint: After carrying out the repair, check that the fault has been remedied.

Warning! If the engine cooling fan (FC) is running, wait until it has stopped.








- Ignition off
- Reinstall the connectors, components etc.
- Connect a voltmeter to generator (GEN) B+ and ground
- Start the engine. Maintain a constant engine speed of approximately 2300 rpm
- Ensure that no additional power consuming components are connected.
Check that the system voltage in the battery and charge circuits is normal. For information about the charge voltage, see Generator (GEN) / Charge regulator [1][2]Specifications.









Is the value OK?

Yes - VERIFIED

No - VERIFICATION FAILED

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VERIFIED - Fault Found

VERIFICATION FAILED - Fault-tracing information

PAPER - No Fault Found

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Fault-tracing information




Information

Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.

Do you want to exit fault-tracing?

Yes - FAULT-TRACING FAILED

No - Attempt New Test

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FAULT-TRACING FAILED - FAULT-TRACING FAILED

Attempt New Test - Checking the generator charge voltage

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