16C900

The voltage supply for component N74 (Soot particulate sensor control unit) is not OK.


Possible cause:

- N74 (Steuergerät Rußpartikelsensor)
Affected functions:

- Power generation

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Test 1: Check component N74 (Soot particulate sensor control unit).

1. Check component N74 (Soot particulate sensor control unit).
Check power supply of component N74 (Soot particulate sensor control unit).
Figure legend

- 1:SCR catalytic converter
- N37/8 (NOx control unit downstream of SCR catalytic converter)
- N74 (Soot particulate sensor control unit)
- N74b1 (Soot particulate sensor)
Test prerequisite

- Battery voltage is OK.
- The fuses are OK.
Test sequence

- Switch off ignition.
- Disconnect connector at component N74 (Soot particulate sensor control unit).
- Measure direct voltage with multimeter between sockets (N74) 1 and (N74) 4
- Switch on ignition.
Specified value

- Voltage [11.0...15.0] V
Question

- Is the measurement value OK?







YES
Inspect CAN link between component N74 (Soot particulate sensor control unit) and component N3/9 (CDI control unit).
The measurement value is OK.If several fault codes regarding CAN communication have occurred, the following causes of the fault are likely

- Short circuit or open circuit of CAN wires
- Voltage supply of component N74 (Soot particulate sensor control unit)
Figure legend

- 1:SCR catalytic converter
- N37/8 (NOx control unit downstream of SCR catalytic converter)
- N74 (Soot particulate sensor control unit)
- N74b1 (Soot particulate sensor)
Test sequence

- Switch off ignition.
- Detach coupling at component N74 (Soot particulate sensor control unit).
- Measure resistance with multimeter between sockets (N74) 2 and (N74) 3
Specified value

- Resistor[55...65]ohms
Question

- Is the measurement value OK?







YES
The measurement value is OK.Possible cause and remedy

- Component N74 (Soot particulate sensor control unit) is defective.
End of test

NO
The measurement value is not OK.Possible cause and remedy

- Inspect lines and connectors between control unit N3/9 (CDI control unit) and component N74 (Soot particulate sensor control unit) for damage loose contact and corrosion, repair if necessary.
End of test

NO
The measurement value is not OK.Possible cause and remedy

- Inspect lines and connectors between control unit N10/1 (Front SAM control unit with fuse and relay module) and component N74 (Soot particulate sensor control unit) for damage loose contact and corrosion, repair if necessary.
End of test