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

ENGINE 276.8 in MODEL 166.063 as of model year 2016 

with CODE 494 (US version) 

Function requirements for refueling intention detection - general points 

• Vehicle speed < 2 km/h
• Vehicle not locked from outside

Refueling intention detection - general points 

The legislator requires that no fuel vapors reaches the open air.

Therefore they are not stored in the fuel tank and in activated charcoal canister. Due to temperature fluctuations the pressure can in increase in the fuel tank to up to 350 hPa.

In order to prevent release of fuel vapors for opening the tank cap, the fuel tank is ventilated before unlocking the fuel filler door over the activated charcoal canister.

The ME-SFI [ME] control unit (N3/10) reads in the following signals for the refueling intention detection:

• Fuel tank pressure sensor 1 (B4/48), pressure in fuel tank
• Fuel tank pressure sensor 2 (B4/49), pressure in the vent line
• Left front door control unit (N69/1) via interior CAN (CAN B), electronic ignition lock control unit (N73), chassis CAN 1 (CAN E1), powertrain control unit (N127) and engine CAN (CAN C1)
  • Request for fuel tank ventilation
  • Refueling intention detection switch status (S62/20)
• Rear SAM control unit (N108) via the interior CAN, the electronic ignition lock control unit, chassis CAN 1, powertrain control unit and engine CAN

• Status of fuel filler flap from tank cap central locking actuator (M14/10)

Function sequence of refueling intention detection 

If the driver confirms the refueling intention detection switch, the CAN signal "Request for fuel tank ventilation" is sent via the CAN network to the ME-SFI [ME] control unit. The LED (LED) in the refueling intention detection switch flashes and a message appears in the IC (A1), which informs the driver so that the fuel tank is bled.

The ME-SFI [ME] control unit checks the current pressure in the fuel tank and starts the ventilation through actuation of the fuel tank shutoff valve (Y58/5). The pressure in fuel tank is relieved over the activated charcoal canister and the fuel vapors are caught there.

The ME-SFI [ME] control unit monitors the pressure in fuel tank over the fuel tank pressure sensors and transmits the CAN signal "Fuel tank bled" for a bled fuel tank via the CAN network to the left front door control unit.

At the same time the CAN signal "Unlock fuel filler door" is sent to the rear SAM control unit.

The rear SAM control unit unlocks the fuel filler door through actuation of the tank cap central locking actuator and transmits the status of the fuel filler door to the ME-SFI [ME] control unit and the left front door control unit.

In the IC a message indicates to the driver that the tank readiness was created. The LED in the refueling intention detection switch now lights up permanently.

This process can take up to 15 minutes according to the pressure in fuel tank.

Overtanking protection 

In the fuel tank muss a residual volume of air must always remain for complete filling with fuel. This will be needed in order to compensate for temperature fluctuations, connected with expansion of the fuel and the fuel vapors. It also prevents excess fuel rises above the ventilation system and escapes into the environment.

In order to provide overtanking protection the fuel vapor shutoff valve is actuated at the same time during actuation of the tank cap central locking actuator (Y75/1), which blocks off operational bleeding of the fuel tank and this way limits the filling volume.

If the red filling process is disconnected and the fuel filler door is closed, the fuel vapor shutoff valve is no longer actuated and the operational bleeding is released again.

Schematic diagram of purge system 

	Electrical function schematic for refueling intention detection		PE47.00-P-2051-97NBH
	Overview of system components for gasoline injection and ignition system with direct injection		GF07.70-P-9998MMM