Function Sequence For Automatic Engine Stop
The engine is switched OFF by ECM when all of the following function requirements are fulfilled:
- Indicator lamp for the stop/start system button lights up (system has no malfunction and stop/start system is activated)
- Vehicle speed: 0 km/h (0MPH)
- Coolant temperature: 60°C - 115°C (140°F - 239°F)
- Engine speed in specified value range
- Transmission oil temperature: 10°C - 120°C (50°F - 248°F)
- Gear range: D or N range
- Accelerator pedal not operated
- Brake pedal operated until vehicle comes to a standstill
- Sufficient vacuum [(- 105) - (- 9) kPa] in brake booster
- Engine hood closed
- No crash signal
- No previous maximum full-stop braking
- Steering wheel angular velocity in the specified value range
- Condition of the on-board electrical system OK
- Driver door closed
- Driver seat belt applied
- Interior temperature regulated
The following control units read in the following sensors and signals for fulfillment of the function requirements.
ECM
- Engine coolant temperature sensor
- Accelerator pedal sensor, accelerator pedal actuation
- Fuel temperature sensor
- Crankshaft position sensor, engine speed
- Supplemental restraint system (SRS) control unit, direct crash signal
Combination meter
- Vehicle speed
SRS control unit
- Indirect crash signal
- Status of driver seat belt
Body control unit (BCM)
- Engine stop precaution
- Engine start request
- Signal that engine hood is closed
- Stop/Start system status button
A/C control
- A/C status
- Engine stop precaution
- Engine start request
Electronic Stability Program control unit
- Wheel speed
- Brake actuation
- Engine stop precaution
- Engine stop release
- Engine start request
Front door control unit (Driver's side)
- Front door contact switch (Driver's side)
Steering column tube module control unit
- Steering wheel angle
- Steering wheel angular velocity
- DISTRONIC electric controller unit, engine torque request (increasing or reducing)
- Fuel pump control module (FPCM), fuel pressure
- TCM, status of gear range
DISTRONIC electric controller unit
- Engine torque request (increasing or reducing)
Fuel pump control module (FPCM)
- Fuel pressure
TCM
- Status of gear range
After an automatic engine stop a maximum of three automatic engine stops are permitted without exceeding the speed threshold of 8 km/h (5 MPH).
After the fourth engine start, the vehicle must exceed a speed of 8 km/h (5 MPH) in the engine stop.
Upon opening of the engine hood in automatic engine stop, the stop/start system is switched off and all indicator lamps in the combination meter light up. The engine must be restarted using the transmitter key or over the stop/start button KEYLESS-GO.