1997 MERCEDES-BENZ ML320 Complete Repair Manual

TPMS reset relay child restraint TPMS alternator belt roof rack

Page 2177 of 4133

MERCEDES-BENZ ML320 1997 Complete Repair Manual Camshaft position (camshaft Hall sensor)
Knock identification:
Engine 104, 111, 112, 113, 119, 120 by means of knock sensors Engine 137 by ionic current
measurement
Engine temperature (c

Camshaft position (camshaft Hall sensor)
Knock identification:
Engine 104, 111, 112, 113, 119, 120 by means of knock sensors Engine 137 by ionic current
measurement
Engine temperature (coolant temperature sensor)
Engine load (hot film air flow sensor or pressure sensor on supercharged engines)
Accelerator pedal position (accelerator pedal sensor)
Precontrol by means of automatic RON switch (internal)
Output signals:
Cylinder specific ignition angle correction on the calculated map value of the ME control unit.
Ignition angle emergency mode if fault identified.
Basic function
The anti-knock control is active from a coolant temperature of 70 °C. If knocking is detected at a cylinder above
an engine load of approx. 40%, its ignition angle is retarded from the next ignition by about 2.3° crank angle
(e.g. M119) or by about 3.0° crank angle (e.g. M120). If knocking continues to be detected, the ignition angle is
continuously retarded in steps of 2.3° crank angle (e.g. M119) until the maximum retardation is reached
(approx. 10 to 15° crank angle, depending on engine speed). In addition, the automatic RON switch influences
the maximum retarding of the ignition timing - the higher the selected RON stage, the less is the maximum
retarding of the ignition timing.
If knocking-free combustion exists, the retardation is reduced in steps of approx. 0.75° crank angle after a few
ignitions (depending on engine speed) until the map value (a) is achieved, or knocking once again occurs.
Adaptation of anti-knock control
The adaptation of the anti-knock control is active from a coolant temperature of approx. 75 °C. Any corrections
required to the ignition angle because of knocking combustion are constantly detected for the specific cylinder
and stored together with the relevant operating state of the engine (engine load/speed range).
The stored adaptation value is taken into account in the output of the individual cylinder angle so that each
cylinder is immediately operated with the optimal ignition angle.
During abrupt acceleration, no values are stored for about 2 seconds in order to avoid any incorrect adaptation
values.
Faults in the case of knocking detection
If no signals are received from the knock sensors or from the ionic current measurement, the ignition angle of
all the c
ylinders is retarded, for safety reasons, by as much as approx. 11° crank angle depending on engine

2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
me
Saturday, October 02, 2010 3:18:54 PMPage 23 © 2006 Mitchell Repair Information Company, LLC.

Page 2178 of 4133

MERCEDES-BENZ ML320 1997 Complete Repair Manual speed and temperature. The anti-knock control and the adaptation are deactivated and a fault is stored.
Automatic RON switch
In addition to the RON correction using the HHT, the anti-knock control f

Page 2179 of 4133

MERCEDES-BENZ ML320 1997 Complete Repair Manual Fig. 16: Identifying Knock Sensors - Engine 112
KNOCK SENSORS, LOCA TION - GF15.12-P-4101-01B
Fig. 17: Identifying Knock Sensors - Engine 113
KNOCK SENSORS, FUNCTION - GF15.12-P-4101-02KE

2001 Me

Page 2180 of 4133

MERCEDES-BENZ ML320 1997 Complete Repair Manual Fig. 18: Identifying Knock Sensors Oscilloscope Signals
Any vibrations which occur are converted with the aid of the piezo ceramic into electrical signals.
Piezo-electric effect: If a mechanical for

Page 2181 of 4133

MERCEDES-BENZ ML320 1997 Complete Repair Manual 112.910 /911 /912 /913 /914 /916 /917 /920 /921 /922 /923 /940 /941 /942 /943 /944 /946 /947 /949 /953 /954 /95
ENGINE 113.940 /941 /942 /943 /948 /960 /961 /963 /965 /966 /967 /968 /969
ENGINE 166.

Page 2182 of 4133

MERCEDES-BENZ ML320 1997 Complete Repair Manual 202.020 /080 as of 1.9.98 with CODE (423a) 5-speed automatic transmission (new-generation)
ENGINE 111.974
with CODE (423a) 5-speed automatic transmission (new-generation)
with CODE (494a) USA vers

Page 2183 of 4133

MERCEDES-BENZ ML320 1997 Complete Repair Manual Task
After engine start speed is reached, interrupt the circuit (circuit 50) M1 to the solenoid switch of the starter.
Design
The solenoid switch of the starter is operated not through the igniti

Task
After engine start speed is reached, interrupt the circuit (circuit 50) M1 to the solenoid switch of the starter.
Design
The solenoid switch of the starter is operated not through the ignition/ start switch S2/1, but in drive position P
or N through the starter relay, by the engine control unit.
The voltage for the starter relay (coil) is supplied through circuit 87. The starter relay is actuated by the engine
control unit through GND.
Function
When the ignition/start switch is operated in the start position, the engine control unit activates an automatic
start control. Once the engine start speed of 400 to 700 rpm is reached, the engine control unit interrupts the
ground actuation to the starter relay and thus the engine start operation.
Once the engine start operation is initiated, shutting off circuit 50 at the ignition/start switch has no effect. The
starter rotates until the specified start speed is reached, or for about 5 seconds at an engine temperature of +80 °
C, for a maximum of 10 seconds if the engine is cold.
SAFETY PRECAUTIONS
SAFETY INFORMATION: ELECTRICAL SYSTEM - ENGINE - AS15.00-Z-9999ZZ
MODEL all
Motor electronics control unit,
location/task/ design/function GF07.61-P-5000F
HFM-SFI control unit,
location/task/design/ function GF07.51-P-4103D
Crankshaft position sensor,
location/task/ design/function GF07.04-P-4116F
Start recognition functionEngine 104,, 111, 112,
113, 137 (via terminal 50)GF07.13-P-3014G
Engine 119, 120 (via
engine speed signal)GF07.13-P-3014F
ETC control unit, location/taskSelector lever position
information P/N and
driving position engaged.
Transmission 722.6GF27.19-P-4012G
Electronic ignition switch
control unit, location/
task/design/functionModel 202 as of 6/97, 208,
210 as of 3/97GF80.57-P-4102A
Model 215, 220GF80.57-P-4102S
Model 203, 209GF80.57-P-4102PP

2001 Mercedes-Benz ML320
1998-2005 ENGINE Electrical System - Engine - 163 Chassis
me
Saturday, October 02, 2010 3:18:54 PMPage 29 © 2006 Mitchell Repair Information Company, LLC.

Page 2184 of 4133

MERCEDES-BENZ ML320 1997 Complete Repair Manual RISK OF DEATH CAUSED BY CONTACT WITH PARTS CONDUCTING HIGH VOLTAGES. - AS15.10-Z-0001-01A
Do not touch parts which conduct high voltages. Persons who wear electronic implants (e.g. heart
pacemakers)

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