Component description for the ME-SFI [ME] control unit

P07.61-3215-11

Model 171

N3/10 ME-SFI control unit

The ME control unit is located in the relay and fuse box in the engine compartment at the rear on the left.

P07.61-3216-01

Models 203, 209

N3/10 ME-SFI [ME] control unit

N10/1 Front SAM control unit with fuse and relay module

The ME control unit is located in the relay and fuse box in the engine compartment at the rear on the left.

P07.61-3217-01

Models 215, 220

K40/7 Right front fuse and relay module

N3/10 ME-SFI [ME] control unit

The ME control unit is located in the right rear relay and fuse box in the engine compartment.

P07.08-2018-07

Design

1, 2, 3 Plug connections for engine

4, 5 Plug connections for vehicle (body)

The ME control unit consists of aluminum and is designed as a shell concept unitary housing.

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Control of fuel injection system

The fuel injectors (Y62) are actuated individually, in line with the firing order (sequentially), on the basis of the input signals and the performance maps stored in the ME-SFI control unit. The ME-SFI control unit calculates the opening times (injection times) of the fuel injection valves.

Control of ignition system

The ME control unit actuates the ignition coils (T1/1-T1/8) in line with input signals and the performance maps stored in the ME control unit. The ME-SFI control unit also calculates the ignition angle values and controls the anti-knock control (AKC).

Controlling the idling speed control

The ME control unit actuates the throttle valve actuator (M16/6) in line with the input signals and the performance maps stored in the ME control unit.

Control of cruise control

The ME control unit actuates the throttle valve actuator for the cruise control function on the basis of the input signals and the position of the cruise control pushbutton switch (S40/4).

Additional cruise control functions are the variable vehicle speed limit (except ) and an individually programmable permanent maximum speed.

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Drive authorization system/immobilizer

The ME-SFI control unit is always equipped with an immobilizer. When the vehicle is locked, the EIS control unit (N73) transmits information over the CAN databus to the ME control unit, which reacts by unlocking the engine control (lockup).

The engine can be started (start enable) only once the vehicle is again unlocked with the authorized key and the EIS control unit transmits a message to this effect over the CAN databus to the ME control unit.

Engine speed signal

The ME-SFI control unit generates the short-circuit proof engine speed signal TNA from the signals supplied by the crankshaft position sensor (L5) and sends it to other control units as follows:

 Square-wave signal with constant on/off ratio

 Maximum current approx. 20 mA

 4 pulses/crankshaft revolution

Fuel consumption signal

The fuel consumption signal is computed from the injection times

(e.g. 8 liters/hour) and the instrument cluster (A1) sends the current fuel consumption in the form of "square-wave pulse packages".

One square-wave pulse corresponds to 0.2 liters/hour.

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Version coding

is used for adapting the ME control unit to different vehicle versions and vehicle equipment by means of matching code numbers. The coding should be performed with STAR DIAGNOSIS. The following vehicle versions or equipment versions can be coded using the variant coding:

 Vehicle model

 National version

Delayed-off running

After switching off the ignition, the ME control unit carries out a computer delayed-off running, in which certain data memory

(e.g. diagnostic fault code memory) is updated. The duration is dependent on the coolant temperature (approx. 4 seconds at 80°C, and about 150 seconds at - 30°C). If the ignition is switched off without starting the engine, the run-on time is always approx. 4 seconds.

Diagnosis/DTC memory

The ME control unit checks its input and output signals for plausibility and recognizes possible faults. The following faults can be distinguished:

 Faults which are permanently present.

 Loose contact faults which occur while driving

The faults can only be read out in the STAR DIAGNOSIS in the

ME control unit and then erased.

Specific functions can be actuated individually for diagnostic purposes. These are listed in the menu points.

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The faults are not erased in the ME control unit after circuit 30 is interrupted.



Various engine operating information is transmitted via the CAN databus by the ME control unit to other control units which are connected to the CAN databus.