Component description for fuel pump control unit - GF47.40-P-2001MMA
ENGINE 157.9 in MODEL 212, 218
View of right rear compartment door sill, model 218
Location
The fuel system control unit is located under the trim of the right rear door sill.
Task
The FSCU carries the internal designation UFPC AMG (U niversal F uel P ump C ontroller for AMG).
The fuel system control unit regulates the fuel pump (M3) according to need and transmits information via the current fuel pressure to the ME-SFI [ME] control unit (N3/10).
Input and output signals
The following input signals are evaluated by the fuel system control unit and appropriate output signals are emitted:
- CAN input signals
- CAN output signals
- Direct input signals
- Direct output signals
CAN input signals
- fuel pump ON
- data for variant coding
CAN output signals
- fuel supply status
- Diagnostic data
Direct input signals
- circuit 15
- circuit 30
- circuit 31
- "Fuel pump ON" ground signal
- fuel pressure sensor signal (B4/7) (model 212), fuel pressure sensor (B4/7) (model 218)
Direct output signals
- fuel pressure sensor (5 V), (model 212), fuel pressure sensor (model 218)
- fuel pressure sensor mass (model 212), fuel pressure sensor (model 218)
- AC signal for fuel pump (phase A)
- AC signal for fuel pump (phase B)
- AC signal for fuel pump (phase C)
Body
The fuel system control unit consists of a fuel housing with two plugs and internal measuring and control electronics.
Function
The function is described at the following points:
- Fuel pump regulation
- Fuel system limp-home mode control unit
- Diagnosis
- Tank-draining function
Fuel pump regulation
Switching on of the fuel pump takes place if a signal "fuel pump ON" is received by the fuel system control unit. This signal is sent redundant;y by the ME-SFI [ME] control unit as a CAN signal via the drive CAN (CAN C) and directly as a ground signal.
The fuel system control unit detects the current fuel pressure by means of a voltage signal from the fuel pressure sensor and transmits this information via the drive train CAN to the ME control unit.
The fuel system control unit evaluates the current fuel pressure, compares it with the specified fuel pressure and actuates the fuel pump appropriately by means of these phase-offset AC voltage signals in such a way that the actual value corresponds to the specified value.
The fuel pump pressure is regulated dependent on the fuel temperature and the engine rpm between about 4.0 and a maximum of 6.7 bar.
Fuel system limp-home mode control unit
- If the signal "Specified fuel pressure" is missing, a substitute value is created by the fuel system control unit and the fuel pump is appropriately actuated.
- if the signal from the fuel pressure sensor is missing the fuel pump is actuated over a consumption-dependent limp-home mode characteristics.
- If the signal "specified fuel pressure" and the signal from the fuel pressure sensor are missing, the fuel pump is actuated by an established replacement voltage.
Diagnosis
The fuel system control unit conducts an own and component check. Recognized errors are stored by the fuel system control unit and sent to the Xentry diagnostics via the diagnostic CAN to the ME-SFI control unit via the drive train CAN.
Tank-draining function
The fuel tank can be emptied over the fuel system control unit without the engine running.
To do this, the tank draining function is selected using Xentry Diagnostics, and the following parameters are entered:
- Parameter 01 for "Fuel pump ON"
- Time "0-99999" seconds
- Specified fuel pressure 5.5 bar
During draining, Xentry Diagnostics must remain connected and the ignition must remain switched on.
Variants
The vehicle and engine variants are already stored in the fuel system control unit. After replacing the fuel system control unit, variant coding must be conducted.
| Designation | Unit | Values | Tolerance range | Remarks |
|---|---|---|---|---|
| Fuel system control unit (N118) | ||||
| Supply voltage | V | 13.5 | Terminal 30 | |
| Voltage limit: Minimum Maximum | V | 6.0 | ||
| V | 16.0 | |||
| Power consumption: No-load current (typical) No-load current (maximum) readiness-to-operate | μA | 7 | at 13 V and 23°C | |
| μA | 300 | |||
| mA | 100 | |||
| mA | 300 | |||
| Reverse polarity protection | Inverse-polarity protection diode between circuit 30 and circuit 31 | |||
| Short-circuit resistance | For power supply, load outputs and signal lines | |||
| Operating temperature range | °C | -40 - 85 | ||
| Diagnosis capability | Yes | |||
| Flash capability/coding capability | Yes/yes | |||
| Special features | De-tanking service (de-tanking without engine running) | |||
| Fuel pressure sensor signal (B4/7) (model 212), fuel pressure sensor (B4/7) (model 218) | ||||
| Type | Capacitive, absolute measuring sensor | |||
| Supply voltage | V | 5.0 | ±0.25 V | |
| Signal voltage | V | 0.3 - 4.5 | Linear, signal proportional to fuel pressure | |
| Measuring range | bar | 0.5 - 10 | ||
| Operating temperature range | °C | -40 - 80 | ||
| Fuel pump (M3) | ||||
| Model | Two-stage flow pump with a 3-phase AC motor | |||
| Supply voltage | V | 12.0 | 3 phase-shifted AC signals from FSCU | |
| Delivery rate maximum | l/h | 130 |
| Wiring diagram for fuel system control unit | N118 MODEL 212 | PE47.40-P-2101-97DAD | |
| N118 Model 218 | PE47.40-P-2101-97XAB |