GF47.00-P-1000MQH Refueling Safety Detection Function

GF47.00-P-1000MQH Refueling Safety Detection Function
- ENGINES 272.973 in MODEL 164.195

Function requirements for refueling safety detection - general points
- Vehicle speed less than 2 km/h
- Vehicle not locked from outside

Refueling safety detection - general points
The fuel vapors are stored in the fuel tank up to 600 hPa. The fuel tank is ventilated before unlocking the fuel filler door to prevent opening the fuel tank cap. The driver can unlock the fuel filler flap over the refueling safety detection switch (N72/1s46).
The rear SAM control unit (N10/8) reads in the fuel filler flap status for the refueling safety detection over the fuel filler door switch (S133/1).

The ME-SFI [ME] control unit (N3/10) reads in the following sensor and signal for refueling safety detection:
- Fuel tank pressure and temperature sensor (B4/25)
- Rear SAM control unit, request for fuel tank ventilation over the interior CAN (CAN B), central gateway control unit (N93) and engine compartment CAN (CAN C)

Function sequence of refueling safety detection
If the driver actuates the refueling safety detection switch in the upper control panel control unit (N72/1) this sends the "Unlock fuel filler flap" CAN signal over the interior CAN to the rear SAM control unit. The LED (light emitting diode) in the refueling safety detection switch flashes on and off. The rear SAM control unit sends the "Bleed fuel tank" CAN signal over the interior and engine compartment CAN to the ME-SFI [ME] control unit.

The ME-SFI [ME] control unit ventilates the fuel tank over the activated charcoal canister through actuation of the tank system shutoff valve (Y58/16). The ME-SFI [ME] control unit also monitors the tank pressure at the same time using the fuel tank pressure and temperature sensor, and transmits the "Bleed fuel tank" CAN signal for a ventilated fuel tank over the engine compartment and interior CAN to the rear SAM control unit.

The rear SAM control unit unlocks the fuel filler flap by actuating the fuel filler flap CL [ZV] motor (M14/10) and thus allows the driver to refuel the vehicle. The LED in the refueling safety detection switch now lights up permanently.

If the fuel filler door is opened using emergency unlocking, the rear SAM control unit is activated (woken up). This asks the ME-SFI [ME] control unit to vent the fuel tank by sending the "Bleed fuel tank" CAN signal. The LED in the refueling safety detection switch goes on.