P07.08-2236-79
Shows model 166.0 |
N118 | Fuel pump control unit |
Location
The fuel system control unit is located on the right below the rear seat.
Task
The fuel system control unit is supplied by the "Continental Automotive GmbH" company and bears the internal designation FSCM-light (Fuel System Control Module-light).
The fuel system control unit regulates the fuel pump (M3) in accordance with requirements and transmits information about the current fuel pressure to the CDI control unit (N3/9).
Input and output signals
The following input signals are evaluated by the FSCU and the respective output signal is issued:
Direct input signals
Direct output signals
CAN input signals
CAN output signals
Direct input signals
Terminal 15
Circuit 30
Circuit 31
Ground signal "Fuel pump ON"
Fuel pressure sensor sensor signal (B47)
Direct output signals
Fuel pressure sensor power supply (5 V)
Fuel pressure sensor ground connection
Fuel pump (12 V) (pulse width modulated signal)
Fuel pump (pulse width modulated signal)
CAN input signals
Fuel pump ON
Fuel specified pressure
CAN output signals
Fuel pressure
Diagnostic data
Body
The fuel system control unit consists of a plastic housing with two plug connections and internal measuring and control electronics.
Function
The function description is subdivided into the following points:
Controlling the fuel pump
Fuel system control unit limp-home mode
Diagnosis
Tank drainage service
Controlling the fuel pump
Switching on of the fuel pump takes place if a "fuel pump ON" signal is received by the FSCU. This signal is sent redundantly from the CDI control unit as a CAN signal via the drive train CAN (CAN C) and as a ground signal.
The fuel system control unit also receives the CAN signal "fuel requirements" from the CDI control unit.
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 CDI control unit.
The fuel system control unit evaluates the current fuel pressure, compares it with the specified fuel pressure and actuates the fuel pump accordingly by means of a pulse width modulated signal in such a way that the actual value corresponds to the specified value.
Depending on the fuel requirements, fuel pressure is varied from about 4.0 bar.
Fuel system control unit limp-home mode
If the "Fuel requirements" signal is missing, the fuel system control unit generates a substitute value and the fuel pump is actuated accordingly
If the "Fuel requirements" signal and the signal from the fuel pressure sensor are missing, the fuel pump is actuated by means of a defined permanent pulse width modulated signal (maximum delivery)
Various limp-home functions ensure that the fuel supply is also provided if the internal control system fails (e.g. processor failure)
Diagnosis
The FSCU performs am own and component check.
Recognized faults are stored by the FSCU and made available via the drive train CAN to the CDI control unit and additionally via the diagnostic CAN (CAN D) to attached diagnostic equipment.
Tank drainage service
The fuel tank can be emptied over the FSCU without the engine running.
To do this, the container draining function is selected using Xentry Diagnostics, and the following parameters are entered:
Parameter 01 for "fuel pump ON"
Time "0-99999" seconds
Duty cycle of the PWM signal to 100%
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 FSCU. After replacement of the FSCU a variant coding must be carried out.
Designation | Unit | Values | Tolerance range | Remarks |
Fuel system control unit (N118) | ||||
Supply voltage | V | 13.5 | ||
Voltage limit values: minimum maximum | V | 6.0 |
| |
Power consumption: No-load current operation, additional operation | mA | 0.1 | ||
Protection | A | 25.0 | ||
Pole reverse 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 | 40,0...85,0 | ||
Diagnosis capability | Yes | |||
Flashability/codablity | Yes/yes | |||
Special features | Tank draining service (tank draining without "circuit 61 ON") | |||
Fuel pressure sensor (B4/7) | ||||
Model | Capacitive, absolute measuring sensor | |||
Supply voltage | V | 5.0 | 0.25 V | |
Signal voltage | V | 0.3...4.5 | Straight-line, a proportional signal to the fuel pressure | |
Measuring range | bar | 0.5...10 | ||
Operating temperature range | °C | -40.0...80.0 | ||
Fuel pump (M3) | ||||
Model | Single-speed displacement pump | |||
Supply voltage: minimum maximum | V | 6.0 | Pulse width modulated signal from the fuel system control unit (N118) | |
Engine 642 minimum delivery rate | l/h | 190 | For 12 volt | |
Flow rate: Engine 642 maximum | l/h | 165 | For 12 volt | |
Flow pressure: Engine 642 maximum | bar | 4.2 | For 12 volt | |
Return flow counter-pressure: Engine 642 maximum | bar | 0.8 | Outlet of the high-pressure pump |