P07.16-4130-79
Illustrated on 447 |
N118 | Fuel system control unit (FSCU) |
Location
The fuel system control unit (FSCU) is installed under the driver's seat.
Task
The fuel system control unit (FSCU) is supplied by "Continental Automotive GmbH" and bears the internal designation FSCM (GEN4Fuel System Control Module Generation 4).
The fuel system control unit (FSCU) regulates the fuel pump with fuel feed module (M3/3) in accordance with requirements and transmits information about the current fuel pressure to the CDI control unit (N3/33).
Input and output signals
The following input signals are evaluated by the fuel system control unit (FSCU) and respective output signals issued:
Direct input signals
Direct output signals
CAN input signals
CAN output signals
Direct input signals
Terminal 15
Terminal 30
Circuit 31
Signal "Fuel pump ON"
Fuel fill level from the fuel pump with fuel feed module
Fuel pressure sensor sensor signal (B4/9)
Direct output signals
Fuel pressure sensor power supply (5 V)
Ground connection (sensor) fuel pump with fuel feed module
Fuel pressure sensor ground connection
AC signal for fuel pump with fuel feed module (phase U)
AC signal for fuel pump with fuel feed module (phase V)
AC signal for fuel pump with fuel feed module (phase W)
CAN input signals
Fuel pump with fuel feed module ON
Fuel specified pressure
CAN output signals
Fuel pressure
Fuel-tank level
Diagnostic data
Body
The fuel system control unit (FSCU) consists of a plastic housing with an aluminum base plate for heat dissipation with two plug connections and internal measuring and control electronics.
Function
The function description is subdivided into the following points:
Regulation of fuel pump with fuel feed module
Limp-home mode for fuel system control unit (FSCU)
Fill level evaluation of fuel tank
Diagnosis
Tank drainage service
Regulation of fuel pump with fuel feed module
Switching on of the fuel pump with fuel feed module takes place when a signal "fuel pump ON" is received by the fuel system control unit (FSCU). This signal is sent redundantly by the CDI control unit as a CAN signal via the drive train CAN (CAN C) and directly as a ground signal. The fuel system control unit (FSCU) detects the current fuel pressure by means of a voltage signal from the fuel pressure sensor and sends this information via drive train CAN to the CDI control unit. To control the fuel pump with fuel feed module, the CDI control unit evaluates the fuel pressure and load requirement and sends the CAN signal "fuel specified pressure" to the fuel system control unit (FSCU). This evaluates the CAN signal and actuates the fuel pump with fuel feed module with a phase-shifted alternating current as required, so that the actual fuel pressure corresponds to the specified value. The fuel pump pressure is regulated dependent on the fuel temperature and engine speed at about 4.0 bar.
Limp-home mode for fuel system control unit (FSCU)
If the CAN signal "Fuel pump ON" and the ground signal "Fuel pump ON" are missing or the signal is implausible, the fuel pump with fuel feed module is switched off.
If the "Fuel specified pressure" signal is missing or is implausible, the fuel pump with fuel feed module is driven with a specified pressure.of 4.0 bar.
If the CAN signal "circuit 15" and the signal "circuit 15" is missing or the signal is implausible, the fuel system control unit (FSCU) and therefore also the fuel pump with fuel feed module is switched off.
Fill level evaluation of fuel tank
The fuel system control unit (FSCU) reads in the values of the sensor integrated in the fuel pump with fuel feed module to compute and evaluate the fill level of the fuel tank.
Based on the resistance values measured in ohms and the nominal volume of the fuel tank, the current fill level is calculated as a percentage and liters and transmitted with the appropriate CAN signal to the CDI control unit. The sensor is also checked for plausibility. In the event of implausible measurements, a fault message is stored in the fault memory and is sent to the CDI control unit in the form of a fill level 0%.
Diagnosis
The fuel system control unit (FSCU) performs an own and component check.
Recognized errors are stored by the fuel system control unit (FSCU) and sent via the drive train CAN to the CDI control unit and to the attached Xentry Diagnostics via the diagnostic CAN ( CAN D).
Tank drainage service
The fuel tank can be emptied over the fuel system control unit (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
Fuel specified pressure 4.0 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 (FSCU). After exchanging the fuel system control unit (FSCU) or the fuel tank, variant coding must be carried out. The fuel system control unit (FSCU) is Star1-compatible.