Component description for the ME-SFI [ME] control unit - GF07.61-P-6000SM
ENGINE 113.986 in MODELS 215, 220
ENGINE 113.987 in MODEL 209
ENGINE 113.988 in MODEL 203
ENGINE 113.989 in MODEL 171
Model 171
The ME control unit is located in the relay and fuse box in the engine compartment at the rear on the left.
Models 203, 209
The ME control unit is located in the relay and fuse box in the engine compartment at the rear on the left.
Models 215, 220
The ME control unit is located in the right rear relay and fuse box in the engine compartment.
Design
The ME control unit consists of aluminum and is designed as a shell concept unitary housing.
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 push-button switch (S40/4).
Additional cruise control functions are the variable vehicle speed limit (except
) and an individually programmable permanent maximum speed.
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.
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.
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.