Component description for the fuel pump control unit

P47.50-2046-06

B4/7 Fuel pressure sensor

N118 Fuel pump control unit

Location

The fuel pump control unit is located on the right in the direction of travel behind the side paneling in the luggage compartment.

Task

The fuel pump is actuated by a PWM signal depending on the fuel pressure.

P47.20-2269-01

N118 Fuel pump control unit

A Plug connection, 4-pin

Pin 1 Terminal 30

Pin 2 Terminal 31

Pin 3 Fuel pump +

Pin 4 Fuel pump -

B Plug connection, 8-pin

Pin 1 not assigned

Pin 2 Actuation of fuel pump by the ME control unit

Pin 3 Drive train CAN, High

Pin 4 Drive train CAN, Low

Pin 5 Circuit 15

Pin 6 Fuel pressure sensor, voltage supply -

Pin 7 Fuel pressure sensor, signal

Pin 8 Fuel pressure sensor, voltage supply +5

Design

The fuel pump control unit consists of a control and power electronics unit housed in a plastic housing with two connectors and a metal plate for heat dissipation. It can be diagnosed, has reverse polarity protection and participates on the sensors data bus.

Function

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 sensors data bus.

If the system pressure detected by the fuel pressure sensor drops below the specified value the switch-on time of the PWM signal is extended. Power consumption, rpm and delivery rate of fuel pump increases.

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The signal from the fuel pressure sensor with the current fuel pressure is read in at the fuel pump control unit and sent to the ME-SFI control unit via the sensors data bus. 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 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.

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The fuel supply system provides a number of different emergency mode functions

 In the case of failure of the sensors data bus specification occurs from the fuel pump control unit if terminal 15 and ground are applied to the fuel pump control unit.

 In the event of simultaneous failure of the sensors data bus and the fuel pressure sensor, a continuous PWM signal is provided by the fuel pump control unit.

 In addition to the sensors data bus, actuation of the fuel pump is also requested via a line.

 Circuit 15 (ignition ON) is reported to the fuel pump control unit.

P54.15-2956-04

F33 Rear prefuse box

F33f91 Fuse 91

G1 Battery

The power supply at terminal 30 is fused (fuse 91).