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General Com m un icat ion About: ETM ZA-VS SL 029 2000 Date: 31
July 2000 PAGE 1 OF 3
Please Initial and Route to the following for information before
filing x Dealer Principal x Foreman x Service Personnel - Initial
Below x Service Manager x Service Admin. x Service Consultant x
Parts Manager x Service Advisor Sales Manager
E-Mail: [email protected] Fax: +27 12 522 2284
Technical Bulletins are available on BMW Intranet at URL: http:/
/bmwza01.w9/vk2
Subject: Defender M52 ETM (Electric Trouble Shooting Manual)
Model: Pre MY99 and MY99 Vehic les. Complaint: Various dealers
requested an after market ETM for the BMW engine
Defender, as only engineering drawings were available. Solution:
An ETM was drafted by the Technical dept. as a fix to the
complaint. The two ETMs are circuit diagrams related to preand-MY99
vehicles.
Included below is a basic explanation of what each components
function is and how it fits into the system.
System DME: The Digital Motor Electronics or MS41.0 as referred
to in BMW Explanation: is the electronic heart of the engine. It
uses various sensors as inputs to
determine the optimum ignition and injection to the engine.
DME Relay: It supplies all the sensors and actuators fitted to
the engine with battery voltage. When the ignition is switched off
the DME first
goes through a shutdown procedure before switching off the DME
relay. Inertia switch: When the vehic le is involved in an accident
the inertia switch
switches off the fuel pump relay on the pre MY99 vehicles and
the DME relay on the MY99 vehicles. That will stop the engine from
running and being a fire hazard. In some isolated cases it may be
triggered by heavy off road riding as well.
Battery voltage: The DME uses this voltage to adapt the sensors
and
actuators to the changing battery voltage for optimum
performance. Ignition switch: It supplies the primary side of the
coils and the DME with
ignition voltage. As soon as the DME receives this signal it
does a self-test, which takes a few milli seconds and gets ready to
start the engine.
Intake air temperature sensor: It measures the air temperature
of the air
entering the engine and in conjunction with the air mass meter
informs the DME of the air mass entering the engine. The DME will
than be able to control the fuel injection quantity to each
injector.
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About: ETM ZA VS SL 029 2000 MIDRAND ZA-VS-2 PAGE 2 OF 3 July
2000
E-Mail: [email protected] Fax: +27 12 522 2284
Technical Bulletin Documents are available on BMW Intranet
Coolant sensor (X6256): This NTC sensor informs the DME and not
the instrument cluster of the coolant temperature. The DME uses
this information for cold starting purposes. (Enriches the air/
fuel mixture during cold starts to aid starting)
Idle actuator: Like the name suggests it control the idling by
varying the
amount of air bypassing the c losed throttle flap. It can adapt
to various loads on the engine. Itll for example increase the
idling when the A/C compressor is switched on.
Fuel injectors: They atomise a calculated amount of fuel into
the intake
system for combustion. They will be switched off if their
relevant coil has a firing fault. That is done for emission
reasons, as the fuel wont burn and might damaged the catalytic
converters, which in this case is not fitted to Defenders.
Ignition coils: They convert the 12V of the battery to a few
thousand volts,
which used to ignite the atomised air/ fuel mixture. Each coils
secondary voltage is monitored by pin 56 of the DME. The DME
recognises what cylinder is firing by looking at the
crankshaft-and-camshaft sensor. When it does not receive the
secondary voltage signal at the correct time it knows that
something is wrong with that specific coil and cuts it and its
relevant injector out.
Fuel pump relay: It is activated by pin 69 of the DME, which is
activated by
the DME relay, and will switch off if the vehicle is involved in
an accident. Tank vent valve: Only on MY99 vehicles. Only the
harness is fitted to these
vehicles. This valve is used in conjunction with a charcoal
canister connected to the tank. When it opens it allows fuel vapour
from the tank through the charcoal canister through the valve to be
vented into intake manifold for emission reasons.
Oxygen sensors: Not fitted on the Defender. It is used to
measure the
exhaust gases for feedback to the DME to enrich or lean out the
mixture. Its done for emission reasons.
Hot film Air mass meter: It measures the air of the air entering
the engine
and in conjunction with the intake air temperature sensor
informs the DME of the air mass entering the engine. The DME will
than be able to accurately control the fuel injection quantity to
each injector.
Vanos valve: it is used to hydraulically vary the inlet camshaft
timing. That
results in smoother lower rpm idling and a flatter torque curve.
Throttle potentiometer: It is used by the DME to recognise the load
on the
engine and it is also used for overrun situations. In other
words if the throttle is c losed and the engine is still rotating
at 4000 rpm the DME knows that the wheels are driving the engine.
This situation is called over run.
240 ohm 2W resistor: That is the path that the coils will follow
to
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About: ETM ZA VS SL 029 2000 MIDRAND ZA-VS-2 PAGE 3 OF 3 July
2000
E-Mail: [email protected] Fax: +27 12 522 2284
Technical Bulletin Documents are available on BMW Intranet
ground. The .5 B wire is only used to see if the relevant coil
has sparked. Refer to ignition coils. Knock sensors: They measure
combustion and will inform the DME if a specific cylinder is
pre-igniting or knocking (pinging). The DME will than retard that
specific cylinders timing by a certain amount and than advance it
again in steps to the programmed value. Camshaft sensor: It is used
as a feedback to the DME to inform it how much the Vanos has moved
the inlet camshaft. This sensor is used in conjunction with the
crankshaft sensor to determine the cylinder recognition and rpm.
Its also the backup to the crankshaft sensor. For this reason,
unlike most other engine management systems the M52 can be started
without the crankshaft sensor. Alternator: The pre MY99 D+ signal
has got a diode inline to the Instrument cluster. Oil pressure:
Switches off the warning light in the cluster if the engine
pressure reaches a certain limit. Temperature sensor: Although it
is housed in the same unit as the DME temperature sensor housing
its dedicated to the instrument c luster. Engine speed: Derived
from the crankshaft sensor and used to drive revcounter gauge.
Road speed: Derived from the speed sensor on the transfer box
and sent to instrument cluster for the Speedo. From there the
signal gets filtered and supplied to the DME for top speed
limiting. If this signal is missing the DME will only rev up to a
specific RPM level and in doing so will stop the vehicle from
reaching its top speed.
Pierre Dieperink Jan Ltter Technical Consultant Product Support
Manager
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Defender M52 ETM(Electric Trouble Shooting Manual)Pre-99 MY99 MY
onwards