Mercedes-Benz ML320. Manual — part 773

GF18.40-P-4111-02A

Oil sensor function

P18.40-2046-12

B40 Oil sensor (oil level, temperature and quality)

Temperature sensor (PT1000)

Capacitive measuring range

Top condenser
CL Capacitive air
COIL

Capacitive engine oil

Bottom condenser

Fill level

Oil level and oil quality are detected on the basis of the capacitance
of the engine oil (dielectric). The oil temperature is detected by the
temperature sensor. All the signals are processed in the electronics
to form a PWM signal and transferred to the engine control unit.

The measuring principle of the oil sensor is a capacitance
measurement, whereby the capacitance is dependent upon the oil
level. The measuring system consists of two cylinder condensers
which possess a metal pipe as a common external electrode. Both
other electrodes are arranged over each other as an inner pipe.
The dielectric constant of the engine oil is determined by the lower
condenser (C2) which is always full of oil (e approximately 2.3 to 4.0).

The fill level (h) is then determined by the upper condenser (C1)
using the dielectric constant. The capacitance of the upper
condenser (C1) is calculated on the basis of a parallel connection
with two condensers which have air and engine oil as a dielectric
material.

The condensers are located in a plastic housing which serves as a
damping cup. The engine oil flows through the feed bore holes into
the housing between the condensers.

The measuring range for the oil level is 80 mm
(normal level

40 mm), accuracy of measurement approx.

3 mm.

The voltage for the oil sensor (approx. 5 V) is supplied by the engine
control unit.

P07.61-0445-05

Signal assignment oil sensor

On/off ratio signals

Okay

Oil temperature

20 to 80%

Oil level

20 to 80%

Oil quality

20 to 80%

On/off ratio signals

>80 %

Oil temperature

> +160 °C

Oil level

>80 mm

Oil quality

e>6

On/off ratio signals

<20 %

Oil temperature

< - 40 °C

Oil level

<0 mm

Oil quality

e< 1

pulse duty factor

100 %

Each information block consists of three successive square-wave
signals, This is followed by a short pause.
A measured variable is assigned to each square-wave signal (A, B,
C). The quantisizing in each case is based on the on/off ratio (T) of
approx. 20 to 80 %.

Because oil level and oil quality (capacitance of the engine oil) are
dependent of each other, this information is first compensated for in
the engine control unit, before it is transmitted via CAN databus to
instrument cluster.

The following faults at the oil sensor are detected by the engine
control unit and entered in the fault memory:
- Duty cycle of a signal less than 17 % or more than 83 %
- Dielectric constant of engine oil longer than 100 seconds greater
than 5.8 (e.g. because of a lot of water in the engine oil).

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Page 1

GF18.40-P-4111A

Oil sensor, location/task/design/function

15.10.96

ENGINE

111.951 /955 /956 /957 /982

ENGINE

112.910 /911 /912 /913 /914 /916 /917 /920 /921 /922 /923 /940 /941 /942 /943 /944 /946 /947 /949 /953 /954 /955
/970 /972 /973 /975

ENGINE

113.940 /941 /942 /943 /948 /960 /961 /963 /965 /966 /967 /968 /969

ENGINE

166.940 /960 /990 /995

P18.40-2104-11

Shown on engine 112, 113 in Model 129, 163, 170, 202, 208, 210,
215, 220
1

Electronics with 3-pin plug connection

B40

Oil sensor (oil level, temperature and quality)

Capacitive measuring range at sensor

Plug connection
Pin 1: output signal
Pin 2: GND
Pin 3: voltage supply

Oil sensor position

Motor 111.951/ 955

GF18.40-P-4111-01GS

M112113 in Model 129, 163, 170, 202, 208,
210, 215, 220 and model 203, 211with 4MATIC

GF18.40-P-4111-01A

M112, 113 in Model 203, 211 without 4MATIC
and model 209

GF18.40-P-4111-01AA

M166

GF18.40-P-4111-01GC

Oil sensor task

Detecting oil level, oil temperature, oil quality

Oil sensor design

The oil sensor consists of:

D Electronics with 3-pin connector

D Capacitive measuring elements

(condensers)

D Temperature sensor.

Oil sensor function

GF18.40-P-4111-02A

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Page 1

GF18.40-P-4111-01A

Oil sensor position

P18.40-0247-06

Location of oil sensor, engine 112, 113 in
model 129, 163, 170, 202, 208, 210, 215, 220
Model 203 with 4MATIC
Model 211 with 4MATIC

B40

Oil sensor (oil level, temperature
and quality)

Copyright DaimlerChrysler AG 05.06.2006 CD-Ausgabe G/10/04 . This WIS print-out will not be recorded by Modification services.

Page 1

BB00.40-P-0229-03A

Multigrade engine oils (Sheet 229.3)

For use in vehicles/engines refer to

Sheet 229.3

Sheet 223.2

BB00.40-P-0223-02A

For specified viscosity grades refer to

Sheet 224.1 (passenger-car engines)

BB00.40-P-0224-01A

Sheet 224.2 (commercial-vehicle
engines)

BB00.40-P-0224-02A

Product name

0W-30

0W-40

5W-30

5W-40

5W-50

Company, town, country

76 Pure Synthetic Motor Oil

ConocoPhillips, Costa Mesa, CA, USA

Addinol Extra light MV 038

Addinol Lube Oil GmbH, Leuna, Germany

Addinol Super light MV 0546

Addinol Lube Oil GmbH, Leuna, Germany

Addinol Super power MV 0537

Addinol Lube Oil GmbH, Leuna, Germany

Agip Eurosport

ENI S.p.A. - Refining & Marketing Division, Rome, Italy

Agip Extra HTS

ENI S.p.A. - Refining & Marketing Division, Rome, Italy

Agip Sint 2000 Evolution

ENI S.p.A. - Refining & Marketing Division, Rome, Italy

Agip Sint Turbodiesel Evolution

ENI S.p.A. - Refining & Marketing Division, Rome, Italy

Agip Synthetic PC

ENI S.p.A. - Refining & Marketing Division, Rome, Italy

Agip Tecsint SL

ENI S.p.A. - Refining & Marketing Division, Rome, Italy

Agip Tecsint SX

ENI S.p.A. - Refining & Marketing Division, Rome, Italy

Alpine topsynth

Mitan Mineralöl GmbH, Ankum, Germany

Antar Excellia LDX 5W40

Total Lubrifiants, Paris, France

AP Supreme Premium 9999 Synthetic

AP Oil International Ltd, Singapore, Singapore

Aral HighTronic

Aral Aktiengesellschaft, Hamburg, Germany

Aral SuperSynth

Aral Aktiengesellschaft, Hamburg, Germany

Aral SuperTronic

Aral Aktiengesellschaft, Hamburg, Germany

Aral SuperTronic G

Aral Aktiengesellschaft, Hamburg, Germany

Autol Carrera

Agip Schmiertechnik GmbH, Würzburg, Germany

Aviasynth

Avia Mineralöl-AG, Munich, Germany

Azmol Leader

Aot Azmol, Berdyansk, Ukraine

Blasol PSP 5W40

Blaser Swisslube AG, Hasle-Rüegsau, Switzerland

BP Euro Plus

BP p.I.c., London, England

BP Visco 5000

BP p.I.c., London, England

BP Visco 5000 Turbo Diesel

BP p.I.c., London, England

BP Visco 7000 GM

BP p.I.c., London, England

BP Visco 7000 Long Life

BP p.I.c., London, England

BP Visco 7000 Special

BP p.I.c., London, England

BP Visco 7000 Sport

BP p.I.c., London, England

Carl Motorenöl Power

Coparts Autoteile GmbH, Essen, Germany

Castrol Formula RS Motorsport 0W-40