ECO Start/Stop Function Energy Management, Function - GF54.10-D-1040HD
MODEL 906 with ENGINE 642 with TRANSMISSION 722.9 with CODE MJ7 (ECO start)
MODEL 906 with ENGINE 651 with TRANSMISSION 722.9 with CODE MJ7 (ECO start)
Function requirements, general
- Engine running and at operating temperature
- Engine hood closed
- Outside temperature > 0 °C
- Battery temperature between 0 and 60 °C
- One-time overspeeding of v = 15 km/h in forward travel
- System diagnosis completed
Energy management for engine start/stop, general
For a stationary vehicle, the engine Start-Stop function switches the engine off automatically and starts it again, as soon as the driver wishes to drive off.
Switching of the engine during standstill periods of the vehicle reduces the fuel consumption and therefore the carbon dioxide emissions. The master control unit for the engine start/stop function is the CDI control unit (N3/28) (with engine 651) or CDI control unit (N3/30) (with engine 642.8) which records and evaluates all influencing factors.
Switching the engine on and off in a conventional manner using the transmitter key (A8/1) is still possible. Immediately after the cold start of the engine, the CDI control unit performs a system diagnosis and evaluates the functional capability of the engine start/stop function. The SAM control unit (N10) additionally checks operation of the participating components. The engine start/stop function encompasses the following subfunctions:
- Function sequence for engine stop
- Function sequence for engine start
- Function sequence for forced engine start
Additional function requirement for engine stop
- Stop enable from CDI control unit
Function sequence for engine stop
As the master control unit for the engine start/stop function, the CDI control unit checks various influencing factors for the stop enable. The on-board electrical system management provides information, which describes the on-board electrical system management status or the requirements for the on-board electrical system. The following information from the on-board electrical system management is provided by the SAM control unit via the interior CAN:
- Condition of the on-board electrical system battery (G1), via the battery sensor LIN (LIN B15) from the battery sensor (B95)
- On-board electrical system status
The CDI control unit evaluates all the relevant data and then issues the corresponding stop enable. The engine is switched off as a result of this.
The brake pedal must be operated when the vehicle is at a standstill.
Function sequence for engine start
Releasing the brake pedal causes the engine to start. The CDI control unit evaluates all relevant influencing factors and then issues the start enable (hot start signal). As soon as the CDI control unit recognizes an engine speed of n = 400 to 700 rpm, it terminates the start procedure. Following an engine stop a maximum of 3 engine starts is permitted without exceeding the speed threshold of v = 8 km/h.
Function sequence for forced engine start
To ensure that the on-board electrical system stability is also available during engine OFF, the CDI control unit can also force the engine to start. A forced engine start is also conducted if, as a consequence of load-intensive consumers, the on-board electrical system stability can no longer be assured.
Load-intensive consumers can be requested by the following systems:
- Supplemental restraint system
- Brake assist and adaptive cruise control systems
- Air conditioning system
- Steering
As soon as the on-board electrical system management is no longer able to ensure on-board electrical system stability, the SAM control unit sends an engine start request via the interior CAN, electronic ignition lock (EIS) control unit (N73) and engine CAN (CAN C) to the CDI control unit. The CDI control unit receives this request and starts the engine. If, following this, the on-board electrical system stability can still not be assured, the engine is no longer switched off. The engine start/stop function is deactivated.
| Component description for battery sensor | B95 | GF54.10-D-2100HD |
| Component description for CDI control unit | ENGINE 651 N3/28 |
GF07.16-D-6000HD |
| Component description for CDI control unit | ENGINE 642.8 with CODE MP6 (Engine version Euro VI) N3/30 |
GF07.16-D-6000HOC |
| Component description for front SAM control unit with fuse and relay module | N10 | GF54.21-D-6070H |
| Electronic ignition/starter switch control unit (EZS), component description | N73 | GF80.57-D-6000H |