S07.10-0045-79
Block diagram |
A1/1 | Instrument cluster (KI) control unit | N118 | Fuel system control unit (FSCU) | |
B11/4 | Coolant temperature sensor | N127 | Drivetrain control unit | |
B37/4 | Accelerator pedal module | N154 | Climate control control unit (with code H06 (Air conditioning system) or with code HH4 (THERMOTRONIC automatic air conditioning)) | |
B70 | Crankshaft Hall sensor | S2 | Ignition lock switch | |
N2/18 | Supplemental restraint system (SRS) control unit | CAN C | Drive train CAN | |
N3/28 | CDI control unit | CAN E | Chassis CAN | |
N15/11 | Fully integrated transmission control (VGS) electric controller unit | CAN HMI | User interface CAN | |
N30/4 | Electronic Stability Program (ESP) control unit | CAN PER | Peripherals CAN | |
N50 | Fuse and relay module control unit (SRM) | CAN V | Vehicle CAN | |
N62 | Parktronic control unit (PTS) | A | Mercedes-Benz | |
N75 | Driver assistance systems control unit | B | Nissan | |
N80 | Steering column tube module (MRM) control unit | C | Default | |
N93 | Central gateway (CGW) | D | Optional |
Function requirements, general
To enable the function, the on-board electrical system management system control unit checks the following function requirements:
Function switched on via ECO start/stop function button
Driver door closed
Seat belt lock closed
Engine hood closed
One-off exceedance of a vehicle speed of 20 km/h
Drive range "4L" not engaged (all-wheel drive)
Defrost button not actuated.
Rear window heater (R1) switched off
System diagnosis completed without faults
On-board electrical system battery (G1) sufficiently charged
On-board electrical system battery temperature 5 °C
Coolant temperature between 19 and 105 °C
Fuel temperature 90 °C
Diesel particulate filter (DPF) regeneration not active
Exhaust gas temperature < 670 °C
Engine management start-stop function, general
For a stationary vehicle, the ECO start/stop function switches the engine off automatically and starts it again, as soon as the driver wishes to drive off. The fuel consumption and thus the exhaust emissions are reduced by cutting out the engine with the vehicle at a standstill.
The CDI control unit (N3/28) continuously performs a system diagnosis and assesses the system conditions for the ECO start/stop function.
It is still possible to stop and start the engine on request by the driver in the conventional way.
All systems participating in the ECO start/stop function constantly check their status and send this to the powertrain control unit (N127) and via the suspension CAN (CAN E) to the CDI control unit.
Engine management Start-Stop function, function sequence
The ECO start/stop function consists of the following partial functions:
Function sequence for automatic engine stop
Function sequence for automatic engine start
Function sequence for forced engine start (a start dictated by the system)
Function sequence for automatic engine stop
The engine is switched off by the CDI control unit if all of the following function requirements are fulfilled:
Vehicle speed = 0 km/h (for automatic transmission)
Vehicle speed 8 km/h (for manual transmission)
Coolant temperature between 60 °C and 115 °C
Transmission oil temperature between 10 °C and 120 °C
Engine rpm in specified value range
Drive range "D" or "N" (for automatic transmission)
Transmission in neutral position (for manual transmission)
Accelerator not operated
Service brake actuated up to vehicle stillstand (for automatic transmission).
Service brake actuated (for manual transmission).
Adequate vacuum in the brake booster
Engine hood closed
No crash signal
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 CDI control unit reads in the following signals for fulfilling the function requirements:
Coolant temperature sensor (B11/4), coolant temperature
Crankshaft Hall sensor (B70), engine speed
Accelerator pedal module (B37/4)
Drive range "D" engaged and service brake actuated
Instrument cluster (IC) control unit (A1/1), vehicle speed
Supplemental restraint system control unit (SRS) (N2/18), direct crash signal
Supplemental Restraint System (SRS) control unit, indirect crash signal
Control unit for climate control (N154) (with code H06 (air conditioning system) or with code HH4 (THERMOTRONIC automatic climate control)), air conditioning system status:
Engine stop prohibition
Engine start request
Electronic Stability Program (ESP) control unit (N30/4):
Brake actuation
Wheel speed
Engine start request
Engine stop release
Engine stop prohibition
PARKTRONIC control unit (PTS) (N62), engine torque request (increase or reduction)
Steering column tube module (MRM) control unit (N80), steering wheel angle and steering wheel angular velocity
Fuel system control unit (FSCU) (N118), fuel pressure
Fully integrated transmission control (VGS) electric controller unit (N15/11) (with code G42 (7G-TRONIC PLUS)), drive range status
After an automatic engine stop a maximum of three automatic engine stops are permitted without exceeding the speed threshold of 8 km/h.
After the fourth engine start, the vehicle must exceed a speed of 8 km/h for the engine to be stopped again.
Upon opening the engine hood in automatic engine stop, the ECO start/stop function is switched off and all indicator symbols in the instrument cluster light up. The engine must be restarted via the ignition lock switch (S2).
Function sequence for automatic engine start
With manual transmission, the engine is automatically started upon actuating the acceleration or clutch pedal. For an A/T the engine is started automatically for release of the brake or actuation of the accelerator pedal.
The CDI control unit controls the circuit 50 starter relay by means of a ground signal. The power contact on the relay closes and the starter’s solenoid switch (M1) is supplied at "circuit 50" with a voltage from "circuit 30".
Via the drive CAN (CAN C), the fuel system control unit (FSCU) receives the "fuel specified pressure" signal from the CDI control unit and actuates the fuel pump with fill level sensor (M3/3) accordingly.
Function sequence for forced engine start (a start dictated by the system)
The forced engine start subfunction is available as a protection function. Here, the engine is force started autonomously (without any action taken by the driver) by the CDI control unit if one of the following function requirements occurs:
on-board network status required
Coolant temperature > 115 °C
Exceeding the engine stop period of a maximum 3min
Air conditioning system requires engine running (e.g. windows fogged up).
Vacuum at brake booster not in the specified range (residual pressure in brake booster falls below -200 mbar)
Driver presence recognition (driver seat belt or driver door is opened)
Change of the steering wheel angle by more than8°
Vehicle speed > 2 km/h in forward travel and immediately upon recognition of rolling backward (for automatic transmission)
Vehicle speed > 8 km/h in forward travel and for reversing (for manual transmission)
System or communication error of the following systems:
Presence of driver
Steering
On-board electrical system
Brake and management systems
Accelerator pedal
For transmission
Starter
Motor
A maneuvering process is recognized for an engaged reverse gear and the ECO start/stop function is deactivated. If the engine is stopped it is force started by the system and the engine stop function is suppressed if it is running.
The ECO start/stop function is subsequently activated again for an engaged forward gear and for exceeding a vehicle speed 15 km/h.
The engine is also started if the driver door is opened, the driver seat belt buckle is opened or the ECO start/stop function is switched off via the ECO start/stop function button.