Fuel pump control unit, function - GF47.20-P-4009-02MB
ENGINE 275.953 in MODEL 221 up to Model Year 8 ENGINE 275.953 in MODEL 216 up to Model Year 8
The fuel pump control unit actuates the fuel pump for the purpose of fuel pressure regulation via a PWM signal. The ME-SFI control unit sends the preset fuel pressure to the fuel pump control unit via the drive train CAN.
If the system pressure detected by the fuel pressure sensor drops below approx. 3.8 bar, for example, the cut-in on time of the PWM signal is extended. Power consumption, RPM and delivery rate of fuel pump increases.
The signal from the fuel pressure sensor with the actual fuel pressure is read in by the fuel pump control unit and sent to the ME-SFI control unit via the drive train CAN. Here, the fuel pressure plausibility is checked and sent to the fuel pump control unit as a preset fuel pressure. If necessary, the PWM signal is adapted for the fuel pump.
The voltage supply at circuit 30 is fused at the rear SAM control unit with fuse and relay module (fuse 128, 25 A).
The fuel supply system provides a number of different emergency mode functions
- In the event of failure of the drive train CAN, the fuel pump control unit specifies a fuel pressure of 3.8 bar when circuit 15 and ground are available at the fuel pump control unit.
- In the event of simultaneous failure of the drive train CAN and the fuel pressure sensor, a continuous PWM signal is provided by the fuel pump control unit.
- In addition to the drive train CAN, actuation of the fuel pump is also requested via a line.
- Circuit 15 (ignition ON) is reported to the fuel pump control unit.
The fuel pump control unit has a fault memory that can be output using STAR DIAGNOSIS.
The fuel pump control unit must be variant coded after each replacement.
For the purpose of thermal conduction, the control unit must be screwed down.