MERCEDES-BENZ ML350 1997 Complete Repair Manual

Fig. 3: Diagnosis Test Oscilloscope / Good Image Contactless High Voltage Distribution Primary Side
(Single Image) Engine Idling
BASIC KNOWLEDGE
SPARK PLUGS, LOCATI ON/TASK/DESIGN/FUNCT ION - GF15.10-P-3101F
ENGINE 104, 111, 112, 113/, 119, 120, 137, 166 (except, 112.96, 113.98/99)
Fig. 4: Identifying Spark Plug


2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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IGNITION COILS, LOCATION - GF15.10-P-3102-01A
Fig. 5: Identifying Cylinder 1 To 6 Ignition Coil - Location On Engine 112
Spark plugs, locationOne or two spark plugs are
located in the cylinder head
per cylinder.
Spark plugs, taskThe spark plugs ignite the
suctioned and compressed
fuel-air mixture due to arcing
between the electrodes.
Spark plugs, designIn the manufacturer's specific
type symbols, all the spark
plug features are assigned (e.
g. heat rating, shape of
seating, thread, width across
flats, electrode material,
spark position).
Spark plugs, functionThe ignition voltage travels to
the spark plugs from directly
connected ignition coils or
over the ignition lines from
the ignition coils causing
arcing in the air gap between
the center and ground
electrodes.

2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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Fig. 6: Identifying Cylinder 1 To 8 Ignition Coil - Location Engine 113
IGNITION COILS, FUNCTION - GF15.10-P-3102-02A
Each spark plug is actuated separately via its own ignition coil by the ME control unit. Both ignition coils of a
cylinder are combined to form a dual ignition coil.
The ME control unit actuates the primary wirings (L1) of the double ignition coils at circuits 1 a or 1 b with
ground.
The primary current flow is interrupted at the moment of ignition timing point. As a result of the sudden
collapse of the magnetic field the ignition voltage is generated in the secondary windings (L2). The ignition
voltage flows through the high voltage connection (4a and 4b) and through the spark plug connector to the
respective spark plug (R4).
The voltage supply of the double ignition coils is protected at circuit 15 (a).
Diodes are built-in to suppress additional ignition sparks when the primary current is switched on.

Because of the diodes, it is not possible to measure the resistance in the secondary windings.

2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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Fig. 7: Identifying Ignition Coils, Function
IGNITION COILS, LO CATION/TASK/DESIGN/FUNCTION - GF15.10-P-3102A
ENGINE
112.910 /911 /912 /913 /914 /916 /917 /920 /921 /922 /923 /940 /941 /942 /943 /944 /946 /947 /949 /953 /954 /9
5
ENGINE 113.940 /941 /942 /943 /948 /960 /961 /963 /965 /966 /967 /968 /969
Fig. 8: Identifying Ignition Coil Components
- Shown On Engine 112

2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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Saturday, October 02, 2010 3:18:54 PMPage 10 © 2006 Mitchell Repair Information Company, LLC.

ME-SFI IGNITION SYSTEM FUNCTION DIAGRAM - GF15.12-P-0001-01A
Fig. 9: Identifying ME-SFI Ignition System Components - Engine 112
ME-SFI IGNITION SYSTEM FUNCTION DIAGRAM - GF15.12-P-0001-01B
Ignition coils, location GF15.10-P-3102-01A
Ignition coils, taskSupplying adequate
ignition energy in all
operating conditions for
the particular ignition
circuit.
Ignition coils, designOne double ignition coil
for each cylinder. Attached
to cylinder head cover.
Ignition coils, function GF15.10-P-3102-02A

2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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Saturday, October 02, 2010 3:18:54 PMPage 11 © 2006 Mitchell Repair Information Company, LLC.

Fig. 10: Identifying ME-SFI Ignition System Components - Engine 113
ME-SFI IGNITION SYSTEM SIGNAL ASSIGNMENT - GF15.12-P-0001-02A

2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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Saturday, October 02, 2010 3:18:54 PMPage 12 © 2006 Mitchell Repair Information Company, LLC.

Fig. 11: Identifying ME-SFI Ignition System Signal Assignment - Signal Assignment Engine 112
ME-SFI IGNITION SYSTEM SING LE ASSIGNMENT - GF15.12-P-0001-02B
Fig. 12: Identifying ME-SFI Ignition System Signal Assignment - Signal Assignment Engine 113

TNA rpm signal on ME2.8 with 3 pulses for each engine revolution
ME-SFI IGNITION SYSTEM FUNCTION - GF15.12-P-0001F
ENGINE 104.941 /943 /944 /991 /994 as of 1.8.96

2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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ENGINE 104.995
with CODE (494a) USA version
with CODE (807) Model year 1997
with CODE (808) Model year 1998
with CODE (498) as of Model Year 97 Japanese version
ENGINE 111.921 /942 as of 1.9.98,
111.943,
111.944 as of 1.8.96,
111.946 as of 1.6.98,
111.947/973,
111.975 as of 1.8.96
ENGINE 111.945
in MODEL 208.335 /435 as of 1.6.98,
202.020/080 as of 1.9.98
ENGINE 111.974
with CODE (494a) USA version
with CODE (807) Model year 1997
with CODE (808) Model year 1998
ENGINE
112.910 /911 /912 /913 /914 /916 /917 /920 /921 /922 /923 /940 /941 /942 /943 /944 /946 /947 /949 /953 /954 /9
5
ENGINE 113.940 /941 /942 /943 /948 /960 /961 /963 /965 /966 /967 /968 /969
ENGINE 119.980 /981 /982 /985
ENGINE 120.982/983
ENGINE 137.970

2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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Saturday, October 02, 2010 3:18:54 PMPage 14 © 2006 Mitchell Repair Information Company, LLC.

Fig. 13: Identifying ME-SFI Ignition System Components
Signal assignment

2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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Fig. 14: Identifying Signal Assignment - Shown On Engine 119
Function
When the crankshaft is rotating, an alternating voltage is generated in the crankshaft position sensor by the teeth
of the driven plate. In this case, each tooth generates an alternating voltage signal. No voltage is generated
through the gap of 2 missing teeth. The ME-SFI control unit detects the TDC position of the crankshaft with the
2nd negative slope after the gap.
If the signal from the camshaft Hall sensor is at 0 V ("low") at this moment, the ME control unit processes this
in order to detect ignition TDC. This, is used for actuating the ignition coils and the fuel injectors. The high
voltage is distributed rotorlessly. Advantages of the rotorless high voltage distribution are:
significantly reduced electromagnetic interference level (no naked sparks)
no rotating parts
reduction in noise
reduced high voltage connections.
1.Determine ignition angle according to input signals, actuate ignition coils and release ignition
spark.
The ME-SFI control unit essentially analyzes the following signals for determining the ignition angle:
EngineRecognition of TDC position of
cylinderIgnition TDC
1111 and 4Cylinder 1
104, 112, 113, 1191 and 6Cylinder 1
120, 137Right hand cylinder bank: 1 and 6Cylinder 1
Left cylinder bank: 7 and 12Cylinder 7

2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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