Part 2

No or incorrect CAN message from control unit N51/2 (ABC control module)

1.1.1.2.13. N118 (Fuel pump control module)

Test 1.1.1.2.13.1: Check power supply at control unit N118 (Fuel pump control module).

1.1.1.2.13.1. Check power supply at control unit N118 (Fuel pump control module).
Possible cause and remedy

- Test fuse, replace if necessary
-
Question

- Is fuse OK?

YES
Test prerequisite

- If other control units also report low-voltage faults, check alternator and governor, repair or replace as necessary.
-
Test sequence

- Switch on ignition.
- Unplug 4-pin connector from component N118 (Fuel pump control module).
- Measure voltage at the unclipped cable.(Ground- Positive)
- Measure direct voltage with multimeter between sockets (N118) 1.2 and (N118) 1.1
Specified values

- Voltage: [11.0 ... 14.5] V
Question

- Is the measurement value OK?

YES
The measurement value is OK.Further possible causes of fault

- Inspect plug connections for corrosion, pinched insulation and loose contact.
End of test

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

- Inspect lead of voltage supply to control module N118 (Fuel pump control module) if necessary for loose contact, damage and corrosion and repair.
End of test

NO
Replace faulty fuse.End of test

1.1.1.2.14. HRA - Headlamp range adjustment
Warning!Communication with ECU required.

1.1.1.3. Resistance test of engine compartment CAN

Test 1.1.1.3.1: Test total resistance of engine compartment CAN.

Test 1.1.1.3.2: Test terminating resistor of component X30/5 (Left voltage distributor (CAN) connector).

Test 1.1.1.3.3: Test terminating resistor of CAN element in control module ME-SFI 2.7.1.

1.1.1.3.1. Test total resistance of engine compartment CAN.
Test total resistance of the CAN engine.
Test sequence

- Switch off ignition.
- Connect socket box to component N3/10 (ME-SFI [ME] control unit).
- Measure resistance with multimeter between sockets (4.11) 96 and (4.1) 86 of the 126-pole socket box tester.
Specified value

- Resistor[55...65]ohms
Question

- Is the measurement value OK?

YES
The measurement value is OK.Further possible causes of fault

- Fault in control unit EZS: Read out fault memory of control unit N73 (EIS [EZS] control unit).
End of test

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

- Line from component N3/10 (ME-SFI [ME] control unit) to component X30/5 (Left voltage distributor (CAN) connector)
- Test terminating resistor of component X30/5 (Left voltage distributor (CAN) connector).
- Test terminating resistor of CAN element in control module N3/10 (ME-SFI [ME] control unit).

1.1.1.3.2. Test terminating resistor of component X30/5 (Left voltage distributor (CAN) connector).
Test terminating resistor of component X30/5 (Left voltage distributor (CAN) connector).
Test sequence

- Switch off ignition.
- Connect socket box to component N3/10 (ME-SFI [ME] control unit).
- Disconnect coupling 4 at component N3/10 (ME-SFI [ME] control unit).
- Measure resistance with multimeter between sockets (4.11) 96 and (4.1) 86 of the 126-pole socket box tester.
Specified value

- Resistor[115...125]ohms
Question

- Is the measurement value OK?

YES
The measurement value is OK.Further possible causes of fault

- Fault in control unit EZS: Read out fault memory of control unit N73 (EIS [EZS] control unit).
- Read out fault memory of control unit N93 (Central gateway control unit).
End of test

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

- Line from component X30/5 (Left voltage distributor (CAN) connector) to component N3/10 (ME-SFI [ME] control unit)
- Component X30/5 (Left voltage distributor (CAN) connector)
End of test

1.1.1.3.3. Test terminating resistor of CAN element in control module ME-SFI 2.7.1.
Test terminating resistor of component ME-SFI 2.8.
Test sequence

- Switch off ignition.
- Connect socket box to component N3/10 (ME-SFI [ME] control unit).
- Connector 4 is plugged in at control unit.
- Unplug the socket 4 from the wiring harness at the socket box.
- Measure resistance with multimeter between sockets (4.11) 96 and (4.1) 86 of the 126-pole socket box tester.
Specified value

- Resistor[115...125]ohms
Question

- Is the measurement value OK?

YES
The measurement value is OK.End of test

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

- Control unit N3/10 (ME-SFI [ME] control unit)
End of test

1.1.2. Engine compartment CAN test

Test 1.1.2.1: Check CAN bus. ( General test information )

Test 1.1.2.2: Voltage supply of engine compartment CAN control modules

Test 1.1.2.3: Resistance test of engine compartment CAN

1.1.2.1. Check CAN bus. ( General test information )
If several fault codes regarding CAN communication have occurred, the following causes of the fault are likely

- Open circuit in voltage supply to the control modules involved
- Short circuit or open circuit of CAN wires
- Connector sleeves of the CAN bus
If CAN communication between control module ME-SFI 2.7.1 and at least one other control module is fault-free, there is no fault at the CAN element of the control module ME-SFI 2.7.1.In this case proceed as follows:

- Read fault memory of control module to which there is a fault in the communication.If a CAN fault regarding communication with control module ME-SFI 2.7.1 is present in this control module, then first of all test CAN lines between the two control modules.

1.1.2.1. No further information available.

1.1.2.2. Voltage supply of engine compartment CAN control modules

Test 1.1.2.2.1: ESM - Electronic selector module

Test 1.1.2.2.2: ME-SFI 2.7.1 - Motor electronics 2.7.1

Test 1.1.2.2.3: ESP - Electronic stability program

Test 1.1.2.2.4: DTR - Distronic

Test 1.1.2.2.5: AIRmatic

Test 1.1.2.2.6: SBC

Test 1.1.2.2.7: EZS - Electronic ignition switch

Test 1.1.2.2.8: IC - Instrument cluster

Test 1.1.2.2.9: SCM [MRM] - Steering column module

Test 1.1.2.2.10: ETC - Electronic transmission control

Test 1.1.2.2.11: SGR - Radar sensors control unit

Test 1.1.2.2.12: TPC - Tire pressure monitor

Test 1.1.2.2.13: N118 (Fuel pump control module)

Test 1.1.2.2.14: HRA - Headlamp range adjustment

1.1.2.2.1. ESM - Electronic selector module
Warning!Communication with ECU required.

1.1.2.2.2. ME-SFI 2.7.1 - Motor electronics 2.7.1
Warning!Communication with ECU required.

1.1.2.2.3. ESP - Electronic stability program
Warning!Communication with ECU required.

1.1.2.2.4. DTR - Distronic

Test 1.1.2.2.4.1: Check power supply of component N63/1 (DTR control module).

Test 1.1.2.2.4.2: Check power supply of component A89 (DTR controller unit).

1.1.2.2.4.1. Check power supply of component N63/1 (DTR control module).
Check power supply at control unit N63/1 (DTR control module).
Test sequence

- Switch off ignition.
- Disconnect coupling 2 at component N63/1 (DTR control module).
- Measure direct voltage with multimeter between sockets (N63/1) 2.8 and (N63/1) 2.4
- Switch on ignition.
Specified value

- [11.0 ... 14.5] V
Question

- Is the value o.k.?

YES
Note

- In the event of stored faults with a high fault frequency count or in the event of customer complaints, check lines and connectors for loose contact and corrosion..
End of test

NO
The measured value is not within the specified value range.Possible cause and remedy

- Cables between component N10/1 (Driver-side SAM control unit with fuse and relay module) and control module A89 (DTR controller unit)

1.1.2.2.5. AIRmatic

Test 1.1.2.2.5.1: Test voltage of terminal 30 at control unit N51 (AIRmatic with ADS control module).

Test 1.1.2.2.5.2: Test of cable for voltage supply

Test 1.1.2.2.5.3: Test procedure ground cable

1.1.2.2.5.1. Test voltage of terminal 30 at control unit N51 (AIRmatic with ADS control module).
Test prerequisite

- Battery voltage is OK.
Status of the relevant actual values:
- Terminal 30:Warning! Communication with ECU required.
Test sequence

- Switch off ignition.
- Connect socket box.
- Switch on ignition.

- Measure direct voltage with multimeter between sockets (2.21) 55 and (2.47) 81 of the 126-pole socket box tester.
Specified value

- [11...14 V]
Question

- Is the measurement value OK?

YES
The measurement value is OK.Note

- In the event of stored faults with a high fault frequency count or in the event of customer complaints, check lines and connectors for loose contact and corrosion..
End of test

NO
The actual value is not o.k.Note

- This test did not produce any clear result.
- Select further tests.

1.1.2.2.5.2. Test of cable for voltage supply
Test prerequisite

- Battery voltage is OK.
Test sequence

- Switch off ignition.
- Connect socket box.
- Switch on ignition.

- Measure direct voltage with multimeter between ground and socket (2.47) 81 of the 126-pole socket box tester.
Specified value

- [11...14 V]
Question

- Is the measurement value OK?

YES
The measurement value is OK.Note

- In the event of stored faults with a high fault frequency count or in the event of customer complaints, check lines and connectors for loose contact and corrosion..
End of test

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

- Lines to component N51 (AIRmatic with ADS control module)
- F34f37 (Fuse 37)
End of test

1.1.2.2.5.3. Test procedure ground cable
Test prerequisite

- Battery voltage is OK.
Test sequence

- Switch off ignition.
- Connect socket box.

- W15/Measure resistance with multimeter between 1 and (2.21) 55 of the 35-pole socket box tester.
Specified value

- [<1ohms ]
Question

- Is the measurement value OK?

YES
The measurement value is OK.Note

- In the event of stored faults with a high fault frequency count or in the event of customer complaints, check lines and connectors for loose contact and corrosion..
End of test

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

- Ground cable
- W15/1 (Ground (right footwell))
End of test