Engine Timing Start-Stop Function - GF07.10-P-1041OGF

Engine 642.8 in MODEL 166 

as of model year 2016 

with CODE B03 (ECO start/stop function) 

Engine 642.8 in MODEL 292 

with CODE B03 (ECO start/stop function) 

The ECO start/stop function is subdivided into the Engine-side and the on-board network side scope.

The " Engine management, start/stop function" subfunction is examined from the point of view of the Engine management.

Information for partial function "Energy management, start/stop function" is documented in the function description "Energy management function".

Function requirements for Engine management, ECO start/stop function, general 

• Engine runs
• Outside temperature in range: -10°C > T < 40°C
• System diagnosis complete and fault-free
• Speed of 8 km/h exceeded once during forward travel
• Speed of 15 km/h exceeded once during forward travel after a maneuvering process

Engine management, ECO 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.

Conventional cut out and starting of the Engine with the transmitter key (A8/1) or via the Start/Stop button KEYLESS-GO (S2/3) (with code (889) Keyless Go) continues to be possible.

The CDI control unit (N3/9) continuously performs a system diagnosis and assesses the system conditions for the ECO start/stop function. All systems participating on the ECO start/stop function permanently check their status and transmit this via the chassis CAN 1 (CAN E1) or drive train CAN (CAN C) to the CDI control unit.

If the function requirements are fulfilled, the driver is notified of start/stop readiness by the "ECO" symbol in the multifunction display (A1p13) in the IC (A1).

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
• Coolant temperature ≥ 70°C for a outside temperature from -30°C up to -10°C
• Coolant temperature ≥ 60°C at an outside temperature of -9°C to 14°C
• Coolant temperature ≥ 15°C for a outside temperature from 15°C up to 60°C
• Coolant temperature < 110°C
• Engine oil temperature ≥ 15°C and ≤ 120°C
• Engine rpm in specified value range
• Transmission oil temperature > 10°C and < 120°C
• Gear range "D" or "N"
• Accelerator not operated
• Service brake actuated up to standstill of the vehicle
• Atmospheric pressure > 760 mbar
• Adequate vacuum (-1150 mbar up to 130 mbar) in 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
• Fill level in fuel tank > 2 l
• Do not overload diesel particulate filter
• Off-road program disabled
• No previous maximum full-stop braking

For the start-stop function the CDI control unit reads in the following signals:

• Engine oil temperature sensor (B1)
• Left fuel tank fuel fill level sensor fuel level indicator (B4/1)
• Right fuel tank fuel level indicator fill level sensor (B4/2)
• Coolant temperature sensor (B11/4)
• Accelerator pedal sensor (B37), accelerator pedal actuation
• DPF differential pressure sensor (B28/8)
• Fuel temperature sensor (B50), fuel temperature
• Crankshaft Hall sensor (B70), Engine rpm
• FESCUE (N118), fuel pressure via the drive train CAN
• Fully integrated transmission control unit (Y3/8n4), engaged gear range via drive train CAN
• Instrument cluster, vehicle speed via chassis CAN 2 (CAN E2), electronic ignition lock control unit (N73) and chassis CAN 1 (CAN E1)
• Supplemental restraint system control unit (N2/10), direct crash signal
• Steering column module control unit, via chassis CAN 1:
• Indirect crash signal
• Status of driver seat belt

SAM control unit (N10) via interior CAN (CAN B), the electronic ignition lock control unit and chassis CAN 1

• Engine stop prohibition
• Engine start request
• Upper control panel control unit (N72/1), status of ECO start/stop function button (N72/1s50) via battery sensor LIN (LIN B15)

Electronic ignition lock control unit and chassis CAN 1:

• Automatic air conditioning control and operating unit (N22/7) via interior CAN, electronic ignition lock control unit and chassis CAN 1:
• A/C status
• Engine stop prohibition
• Engine start request

Electronic Stability Program control unit (N30/4) via chassis CAN 1:

• Wheel speed
• Brake vacuum sensor (B64/1)
• Brake light switch (S9/1)
• Engine stop prohibition
• Engine stop release
• Engine start request

AIRMATIC control unit (N51/3) via chassis CAN 1 (with CODE 489 (AIRMATIC)):

• Engine stop prohibition
• Engine start request

Radar sensors control unit (N62/1) (with CODE 23P (Driving assistance package)):

• Engine torque increase request
• Engine torque reduction request

Left front door control unit (N69/1) via interior CAN, electronic ignition lock control unit and chassis CAN 1

• Engine stop prohibition
• Driver door closed

Steering column tube module control unit (N80), via chassis CAN 1

• Steering wheel angle
• Steering wheel angular velocity

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 in the Engine stop.

Upon opening of the Engine hood in automatic Engine stop, the ECO start/stop function is switched off and all indicator lamps in the IC light up. The Engine must be restarted using the transmitter key or over the start/stop button KEYLESS-GO (with code (889) Keyless Go).

Function sequence for automatic Engine start 

The Engine is automatically started upon releasing the brake or actuating the accelerator pedal.

The CDI control unit actuates the circuit 50 starter relay (F58kM) by means of a ground signal. The power contact on the relay closes and the starter solenoid switch (M1) is supplied at "circuit 50" with a voltage from "circuit 30".

The fuel system control unit receives the CAN signal "Fuel specified pressure" from the CDI control unit via the drive train CAN and actuates the fuel pump (M3) with a pulse width modulated signal 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 condition requires the Engine to run
• Coolant temperature > 125°C
• Exceeding of the Engine stop period of a maximum of 3 minutes
• A/C required Engine running (e.B. windshield fogged up)
• Vacuum at BAS brake booster not in the nominal range (-1150 to 130 mbar)
• Driver presence recognition
• Change of the steering wheel angle by more than 8°
• Vehicle speed >2 km/h for forward travel and immediately for recognition of rolling backwards
• System or communication error from one of the following systems: driver presence, steering, on-board electrical system, brake system, accelerator pedal, transmission, starter, Engine, chassis

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 seat belt buckle for the driver is unfastened or the ECO start/stop function is switched off.

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