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P20E8


N91 (ECI ignition system mains unit) (P0300)

Test 1: Test ignition system.

1. Test ignition system.
Safety note
Warning!Hazard as a result of high voltage at the ignition system!

- Electronic ignition systems operate within a hazardous power range both at the low voltage side (primary circuit) as well as on the high voltage side (secondary circuit).
- Contacts with such parts can result in burns, heart flutter or cardiac arrest.
Rules of conduct and protective measures

- Persons with heart pacemakers must not perform any work on the ignition system.
- Switch off the ignition when performing work on the ignition system.
- Do not touch any parts of the ignition system when starting the engine or when the engine is running.
- Wear protective shoes with rubber soles.
- Do not install any uninsulated adapters into the ignition cables.


Important note

- During the starting procedure, undervoltage may cause the left or right ECI ignition module or both ignition modules to cut out.


Test 1.1: Check power supply of component N91 (ECI ignition system mains unit).

Test 1.2: Check power supply of component N92/1 (ECI ignition module, right bank of cylinders).

Test 1.3: Check power supply of component N92/2 (ECI ignition module, left bank of cylinders).

1.1. Check power supply of component N91 (ECI ignition system mains unit).
Check power supply of component N91 (ECI ignition system mains unit).
Test sequence

- Switch off ignition.
- Disconnect connector at component N91 (ECI ignition system mains unit).
- Measure direct voltage with multimeter between sockets (N91) 11 and (N91) 5
- Measure direct voltage with multimeter between sockets (N91) 14 and (N91) 4
- Switch on ignition.
Specified value

- Voltage[11.0...14.5] V
Question

- Are the measurement values OK?







YES
The measurement values are OK.End of test

NO
The measurement values are not OK.Possible cause and remedy

- X4/22f3 (fuse 3)
- Lines
End of test

1.2. Check power supply of component N92/1 (ECI ignition module, right bank of cylinders).

Test 1.2.1: Test voltage supply of circuit 87.

Test 1.2.2: Test auxiliary voltage for ionic current measurement.

Test 1.2.3: Test primary voltage supply.Danger! High Voltage

1.2.1. Test voltage supply of circuit 87.
Test voltage supply of circuit 87.
Test prerequisite

- The power supply of component N91 (ECI ignition system mains unit) is OK.
Test sequence

- Switch off ignition.
- Disconnect connector at component N92/1 (ECI ignition module, right bank of cylinders).See fig.
- (N92/1)Measure direct voltage with multimeter between sockets 8 and 15(N92/1)
- Switch on ignition.
Specified value

- Voltage[11.0...14.5] V
Question

- Is the measurement value OK?













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

- Test auxiliary voltage for ionic current measurement.
- Test primary voltage supply.


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

- K40/7kK (Engine electronics and chassis relay)
- Lines


1.2.2. Test auxiliary voltage for ionic current measurement.
Test auxiliary voltage for ionic current measurement.
Test prerequisite

- The power supply of component N91 (ECI ignition system mains unit) is OK.
Test sequence

- Switch off ignition.
- Disconnect connector at component N92/1 (ECI ignition module, right bank of cylinders).See fig.
- (N92/1)Measure direct voltage with multimeter between sockets 8 and 14(N92/1)
- Switch on ignition.
Specified value

- Voltage[21.0...25.0] V
Question

- Is the measurement value OK?













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

- Test primary voltage supply.


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

- Lines
- N91 (ECI ignition system mains unit)


1.2.3. Test primary voltage supply.Danger! High Voltage
Test primary voltage supply.
Test prerequisite

- The power supply of component N91 (ECI ignition system mains unit) is OK.
Test sequence

- Switch off ignition.
- Wait for at least 3 min.
- Disconnect connector at component N92/1 (ECI ignition module, right bank of cylinders).See fig.
- (N92/1)Measure direct voltage with multimeter between sockets 8 and 16(N92/1)
- Switch on ignition.
Specified value

- Voltage[175...190] VDanger! High Voltage
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

- Lines
- N91 (ECI ignition system mains unit)


1.3. Check power supply of component N92/2 (ECI ignition module, left bank of cylinders).

Test 1.3.1: Test voltage supply of circuit 87.

Test 1.3.2: Test auxiliary voltage for ionic current measurement.

Test 1.3.3: Test primary voltage supply.Danger! High Voltage

1.3.1. Test voltage supply of circuit 87.
Test voltage supply of circuit 87.
Test prerequisite

- The power supply of component N91 (ECI ignition system mains unit) is OK.
Test sequence

- Switch off ignition.
- Disconnect connector at component N92/2 (ECI ignition module, left bank of cylinders).Image with key F7
- (N92/2)Measure direct voltage with multimeter between sockets 8 and 15(N92/2)
- Switch on ignition.
Specified value

- Voltage[11.0...14.5] V
Question

- Is the measurement value OK?













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

- Test auxiliary voltage for ionic current measurement.
- Test primary voltage supply.


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

- K40/7kK (Engine electronics and chassis relay)
- Lines


1.3.2. Test auxiliary voltage for ionic current measurement.
Test auxiliary voltage for ionic current measurement.
Test prerequisite

- The power supply of component N91 (ECI ignition system mains unit) is OK.
Test sequence

- Switch off ignition.
- Disconnect connector at component N92/2 (ECI ignition module, left bank of cylinders).Image with key F7
- (N92/2)Measure direct voltage with multimeter between sockets 8 and 14(N92/2)
- Switch on ignition.
Specified value

- Voltage[21.0...25.0] V
Question

- Is the measurement value OK?













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

- Test primary voltage supply.


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

- Lines
- N91 (ECI ignition system mains unit)


1.3.3. Test primary voltage supply.Danger! High Voltage
Test primary voltage supply.
Test prerequisite

- The power supply of component N91 (ECI ignition system mains unit) is OK.
Test sequence

- Switch off ignition.
- Wait for at least 3 min.
- Disconnect connector at component N92/2 (ECI ignition module, left bank of cylinders).Image with key F7
- (N92/2)Measure direct voltage with multimeter between sockets 8 and 16(N92/2)
- Switch on ignition.
Specified value

- Voltage[175...190] VDanger! High Voltage
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

- Lines
- N91 (ECI ignition system mains unit)


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