Page 2161 of 4133
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
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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.
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1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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Page 2163 of 4133

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.
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1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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Page 2164 of 4133
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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Page 2165 of 4133
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
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1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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Page 2166 of 4133
Fig. 10: Identifying ME-SFI Ignition System Components - Engine 113
ME-SFI IGNITION SYSTEM SIGNAL ASSIGNMENT - GF15.12-P-0001-02A
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Page 2167 of 4133
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
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Page 2168 of 4133
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
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1998-2005 ENGINE Electrical System - Engine - 163 Chassis
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