sensor MERCEDES-BENZ ML320 1997 Complete Repair Manual

Fig. 318: Identifying Active Service System (ASSYST) Display
ACTIVE SERVICE SYSTEM (ASSYST) INFLUENCING PARAMETERS - GF00.20-P-0003-05A
The values of various influencing parameters are required by ASSYST for calculating the demand-based service
interval, and these are included in the calculation of the service interval as weighting factors . There are two
versions within ASSYST, the difference being in the oil level sensors fitted:
The familiar oil level indicator switch (S43) is fitted to engines (104, 111, 119, 120, 602.982, 604, 605,
606). In view of the fact that this is a switch, it is only possible to detect if the oil level drops below the
minimum level.
The oil sensor (oil level/temperature/quality, B40) is used on more recent engines (e.g. 112, 113, 166,
611, 668). This sensor consists of 2 capacitor systems with the engine oil as an insulator. If the water
content of the oil or the oil level changes, there is a change in the capacitance of the "capacitor".
The capacitance is thus a measure for the oil level.
In addition, the oil sensor (oil level/temperature/quality, B40) contains a temperature sensor which
detects the temperature of the engine oil.
All the signals are processed in the electronics integrated in the sensor to form a PWM (pulse width
modulated) signal, and passed to the engine control module (N3).
In addition to the weighting factors, which depend on reallife driving conditions, quality factors are also used
for calculating the demand-based service interval (remaining distance and remaining time).
Survey of ASSYST influencing parameters
Weighting factors (dependant on reallife driving conditions):
Load torque
Engine speed
Oil level
Engine oil temperature
Oil correction factor (is used as comparative value for determining oil level)
Coolant temperature
These data are supplied by the injection system control module (N3) to the service microprocessor over
the CAN.
The data relating to oil level, engine oil temperature and oil correction factor are supplied by the oil
sensor (oil level/temperature/quality, B40) through the injection system control module (N3), and are
therefore only available on engines fitted with this sensor.
Quality factors (these are factory-set to base values and can be changed with the HHT, if operating
conditions of the vehicle so necessitate; they influence the start distance):

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Engine version factor (gasoline/diesel)
National factor (The kilometer or mileage is coded in accordance with the national version.)
Distance travelled :
ASSYST is supplied with the 4 wheel speeds from the traction systems control module (N47) over the
CAN for calculating the distance travelled.
Time
ASSYST is supplied with the time information from the clock integrated in the instrument cluster.
ACTIVE SERVICE SYSTEM (ASSYST) SURVEY MODEL/ENGINE/SENSOR/INSTRUMENT CLUSTER - GF00.20-P-0003-
06A
The table below (status: March 1999) lists the various vehicle models with the different engines and the
different oil level sensors.
In addition, the table also indicates whether an instrument cluster with multifunction display is fitted.
ModelEngineOil level sensorMultifunction display
with engine
129112, 113
103, 104, 119, 120Oil sensor (oil
level/temperature/quality, B40)
Oil level indicator switch S43-
140-
104, 119, 120, 606Oil sensor (oil
level/temperature/quality, B40)
Oil level indicator switch S43-
163112, 113, 612
111Oil sensor (oil
level/temperature/quality, B40)
Oil level indicator switch S43-
168166, 668
-Oil sensor (oil
level/temperature/quality, B40)
Oil level indicator switch S43-
170112
111Oil sensor (oil
level/temperature/quality, B40)
Oil level indicator switch S43-
202112, 113, 611
104, 111, 601, 604,
605Oil sensor (oil
level/temperature/quality, B40)
Oil level indicator switch S43-
208112, 113
111Oil sensor (oil
level/temperature/quality, B40)
Oil level indicator switch S43Engine 112 only and
Gulf States: engine 111
210112, 113, 611
104, 111, 602, 605,
606Oil sensor (oil
level/temperature/quality, B40)Engines 112,113 Gulf
States, , : on all
engines fitted; others:

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ACTIVE SERVICE SYSTEM (ASSYST) FUNCTION DESCRIPTION CONTENTS - GF00.20-P-0997AZ
MODEL 129 as of 1.6.97
MODEL 140 as of 1.6.97
MODEL 163
MODEL 168
MODEL 170 as of 1.6.97
MODEL 202 as of 1.6.97
MODEL 208 up to 31.7.99
MODEL 210.081 /281 /025 /063 /065/225 /265 /663 up to 31.5.97
MODEL 210 as of 1.6.97 up to 30.6.99
block diagram
Active service system (ASSYST)
display facilities GF00.20-P-0003-04A
Active service system (ASSYST)
influencing variables GF00.20-P-0003-05A
Active service system (ASSYST)
survey of
model/engine/sensor/instrument
cluster GF00.20-P-0003-06A
Remaining distance function GF00.20-P-2007A
Remaining time function GF00.20-P-2008A
Engine oil monitor function GF00.20-P-2009A
Displaying service functionModel 129, 202 as of
8.99
Model 163 as of 1.00
Model 168 as of 9.99
Model 170 as of 12.99GF00.20-P-2010B
Active service system (ASSYST)
functionEngines with oil sensor
(e.g. 112, 113, 611)GF00.20-P-0003A
Model 210 as of
01.03.97 with engine
111, 602, 604, 605, 606
Model 129, 140, 170,
202 as of 06.97 except GF00.20-P-0003B

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engine 112, 113, 611,
612
(Valid for engines with
oil level switch.)
Active service system (ASSYST)
operating informationEngines with oil sensor
(e.g. 112, 113, 611)GF00.20-P-0003-01A
Model 210 as of
01.03.97 with engine
111, 602, 604, 605, 606
Model 129, 140, 170,
202 as of 06.97 except
engine 112, 113, 611,
612
(Valid for engines with
oil level switch.)GF00.20-P-0003-01B
Active service system (ASSYST)
block diagram GF00.20-P-0003-03A
Active service system (ASSYST)
display facilities GF00.20-P-0003-04A
Active service system (ASSYST)
influencing variables GF00.20-P-0003-05A
Active service system (ASSYST)
survey of
model/engine/sensor/instrument
cluster GF00.20-P-0003-06A
Remaining distance function GF00.20-P-2007A
Remaining time function GF00.20-P-2008A
Displaying service functionModel 129, 202 as of
8.99
Model 163 as of 1.00
Model 168 as of 9.99
Model 170 as of 12.99GF00.20-P-2010B
Engine oil monitor functionEngines with oil sensor
(e.g. 112, 113, 611)GF00.20-P-2009A
Model 210 as of
01.03.97 with engine
111, 602, 604, 605, 606
Model 129, 140, 170,
202 as of 06.97 except
engine 112, 113, 611,
612
(Valid for engines with
oil level switch.)GF00.20-P-2009B
Instrument cluster (IC) function
description contents GF54.30-P-0997AZ

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REMAINING DISTANCE FUNCTION - GF00.20-P-2007A
MODEL 129 as of 1.6.97
MODEL 140 as of 1.6.97
MODEL 163
MODEL 168
MODEL 170 as of 1.6.97
MODEL 202 as of 1.6.97
MODEL 208 up to 31.7.99
MODEL 210 as of 1.3.97 up to 30.6.99
The service intervals which are possible with ASSYST range
on engines with oil sensor (e.g. 112, 113, 166, 611) between 15 000 and 30 000 km,
for the new direct injection diesel engine 668 between 20 000 and 40 000 km,
for engines with oil level switch between 15 000 and 22 500 km (for engine 602.982 between 20 000 and
30 000 km).
The service interval achieved depends on the start distance and the driving conditions (cf. remaining
distance).
Start distance and remaining distance
Start distance refers to the service interval in km/miles which is the minimum distance which may be driven
until the next service. On engines with oil sensor (e.g. 112, 113, 166, 611, 668) this applies only, however, if the
specified quantity of oil has been added during the oil change.
The start distance is dependent on:
the set quality factors
(The quality factors are factory-set to a basic setting. They can be altered with the HHT, if operating
conditions so necessitate.)
The start distance is not dependent on the driving conditions (weighting of the distance driven) and on any oil
replenishments .
The standard value is normall
y 15 000 km, for the new direct injection diesel engine 668 20 000 km.

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The figure may differ from this, however, depending on quality factors.
The start distance is automatically reset to its initial value by the oil change reset each time the oil is changed.
The start distance is an internal computed quantity and cannot be displayed in the instrument cluster. It is
possible to display the start distance with the HHT.
What is normally displayed in the instrument cluster is the remaining distance .
The remaining distance is the same as the start distance immediately after the oil change. On engines with oil
sensor (e.g. 112, 113, 166, 611, 668) this applies only, however, if the specified quantity of oil has been added
during the oil change.
The remaining distance is the distance which remains from the current kilometer reading until the next
service. The possible length of the interval is at least as great as the remaining distance displayed
immediately after an oil change, and is at the most twice the start distance.
The remaining distance is dependent on
the start distance
the driving conditions (a weighting of the distance driven takes place)
any oil replenishments in the case of engines with oil sensor (e.g. 112, 113, 166, 611, 668)
Consequently, ASSYST also takes into account the driving conditions: In the case of a favorable weighting
(e.g. small number of cold starts, no high engine revs, small number of short-distance trips, minimum extent of
towing a trailer etc.) and oil replenishments, the driver is provided with a bonus which extends the remaining
distance and thus the service interval. Account is also taken of whether the vehicle is actually driven or whether
the engine runs at idle speed. ASSYST is constantly supplied with the data regarding the current operating
conditions of the vehicle for this purpose.
In the case of the best weighting , only 0.6 km are added for each kilometer driven.
In the case of the most unfavorable weighting of the distance (e.g. frequent short-distance trips, large number
of cold starts), the remaining distance and thus the service interval is smaller than in the case of the most
favorable weighting (assuming identical quality factors).
In the case of the most unfavorable weighting, up to 3 km are added for each kilometer driven.
The start distance and the remaining distance are once again presented in the form of a graph in the diagram
opposite, taking the example of gasoline engines
Each time the oil is changed, the start and remaining distances are set to the initial value. In this case, the
normal value of 15 000 km is entered as the start distance (top bar) (shaded + dark section). The start distance
may differ from 15 000 km (e.g. 14 000 km; shaded section) if the quality factors do not correspond to the basic
setting. In the case of engines fitted with oil sensor (e.g. 112, 113, 166) the start distance may also be less than
15 000 km if the specified oil quantity was not added during the oil change. The remaining distance (bottom
bar) is always 15 000 km, however, immediately after an oil change. In addition, the service interval is
always at least 15 000 km .

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The total remaining distance and thus the service interval may be increased to not more than twice the start
distance, 30 000 km in this case (white section) as a result of corresponding bonuses (favorable weighting of
distances driven) and in the case of engines fitted with oil sensor (e.g. 112, 113, 166).
Fig. 321: Start And Remaining Distance Graph

However, a start distance of less than 15 000 km results in a reduction in the maximum attainable service
interval.
Refer also to the diagrams in the document "Engine oil monitoring".
Warning threshold (km)
With the HHT it is possible to set a warning threshold between 250 km and 8000 km for the remaining distance.
This warning threshold is set differently for 3 different distances driven. The system adjusts to the correct
annual distance driven by calculating the daily distance driven (refer to table):
Display of remaining distance (The readout is shown in kilometers or miles depending on the national code.):
at driver request
automatically, after 5 s start switch in position 2 or driving if the warning threshold is reached :
The warning symbol and the readout: "SERVICE IN .... KM" appears for 10 s. (On models not fitted with
multifunction display, the service symbol appears together with the remaining distance in kilometers,
from mid July 97 "... km".)
automatically, after 5 s start switch in position 2 or driving if the remaining distance is exceeded :
In this case, the readout "KM .... EXCEEDED" appears together with the service symbol for 30 s (up to
mid July 97 for 10 s). (On models not fitted with multifunction display, the service symbol appears
together with the remaining distance with a negative sign in kilometers as a flashing display, as of mid
July 97 "... km".)
As of approx. 06.97 a brief warning signal sounds in addition.

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The remaining distance is displayed with a resolution of 100 km.
If a speed limit is set at the cruise control, the speed limit appears for a short moment in the display before
the ASSYST text.
In the normal case, it is the remaining distance which is displayed. However, the time information is always
processed in the background to enable the attention of "low-mileage drivers" to be drawn to any service due.
The remaining distance is compared each day with the remaining time. In certain circumstances, the display
switches over, and it is the remaining time which is displayed ( see document "Remaining time").
If certain measured values are not supplied to the ASSYST system, e.g. because of failure of a sensor, it
switches over to stored substitute values. A corresponding entry is made in the fault memory of the relevant
control module.
The data are retained if the operating voltage is disconnected or fails.
REMAINING TIME FUNCTION - GF00.20-P-2008A
Active service system
(ASSYST) operating
informationEngines with oil sensor
(e.g. 112, 113, 611)GF00.20-P-0003-01A
Model 210 as of 01.03.97
with engines 111, 602,
604, 605, 606
Model 129, 140, 170, 202
as of 06.97 except engine
112, 113, 611
(Valid for engines with
oil level switch.)GF00.20-P-0003-01B
Active service system
(ASSYST) display
facilities GF00.20-P-0003-04A
Remaining time function GF00.20-P-2008A
Engine oil monitor
functionEngines with oil sensor
(e.g. 112, 113, 611)GF00.20-P-2009A
Model 210 as of 01.03.97
with engines 111, 602,
604, 605, 606
Model 129, 140, 170, 202
as of 06.97 except engine
112, 113, 611
(Valid for engines with
oil level switch.)GF00.20-P-2009B
Displaying service
functionModel 129, 202 as of 8.99
Model 163 as of 1.00
Model 168 as of 9.99
Model 170 as of 12.99GF00.20-P-2010B

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Warning threshold (in days)
With the HHT it is possible to set a warning threshold of between 5 and 30 days for the remaining time, with a
stepwidth of one day. The basic setting is 30 days.
Display of remaining time
The remaining time is always only displayed in those cases where the following condition is met:
Remaining time (in days) x 40 < remaining distance (in km), and the warning threshold is reached.
The remaining time is displayed in the following cases:
automatically, after 5 s start switch in position 2 or driving, if the warning threshold is reached:
The service symbol and the readout "SERVICE IN ... DAYS" appears for 10 seconds. (On vehicles not
fitted with multifunction display, the current remaining time, the service and the clock symbol appear.)
automatically, after 5 s start switch in position 2 or driving, if the remaining time is exceeded:
The service symbol and the readout "DAYS ... EXCEEDED" appears for 30 s (for 10 s up to mid-July
97). (On vehicles not fitted with multifunction display, the service and the clock symbol appear. The
"remaining time" is displayed with a negative sign (minus sign). The readout flashes in this case.)
After the display reaches the maximum readout of -730 days, the readout remains at this figure! The
readout is displayed with a resolution of 1 day.
As of approx. 06.97 a brief warning signal sounds in addition.
at driver request. The readout is then displayed, as above, for 10 s.
If a speed limit is set at the cruise control, this speed limit is displayed for a short moment before the
ASSYST display.
If certain measured values are not supplied to the ASSYST, e.g. because of failure of a sensor, it switches to
stored substitute values. An appropriate entry is then made in the fault memory of the particular control module.
If the power supply fails, the data are retained. The times without operating voltage (battery disconnected) are
not recorded, however! They can be retroactively included, however, with the HHT.
Active service system
(ASSYST) operating
informationEngine with oil sensor
(e.g. 112, 113, 611)GF00.20-P-0003-01A
Model 210 as of 01.03.97
with engines 111, 602,
604, 605, 606
Model 129, 140, 170, 202 GF00.20-P-0003-01B

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ENGINE OIL MONITOR FUNCTION - GF00.20-P-2009A
MODEL 129 with ENGINE 112, 113
MODEL 163 with ENGINE 112, 113, 612
MODEL 168 with ENGINE 166, 668
MODEL 202 with ENGINE 112, 611
MODEL 208 up to 31.7.99 with ENGINE 112, 113
MODEL 210 up to 30.6.99 with ENGINE 112, 113, 611
General
The oil level is constantly monitored by the oil sensor, and the appropriate data transmitted to the processor by
the ASSYST.
Oil replenishments are detected automatically and result in a bonus, which extends the service interval
accordin
gly.
as of 06.97 except engine
112, 113, 611
(Valid for engines with
oil level switch.)
Active service system
(ASSYST) display
facilities GF00.20-P-0003-04A
Remaining distance
function GF00.20-P-2007A
Engine oil monitor
functionEngine with oil sensor
(e.g. 112, 113, 611)GF00.20-P-2009A
Model 210 as of 01.03.97
with engines 111, 602,
604, 605, 606
Model 129, 140, 170, 202
as of 06.97 except engine
112, 113, 611
(Valid for engines with
oil level switch.)GF00.20-P-2009B
Displaying service
functionModel 129, 202 as of 8.99
Model 163 as of 1.00
Model 168 as of 9.99
Model 170 as of 12.99GF00.20-P-2010B

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