FUSO 4M4 – INTAKE AND EXHAUST – STRUCTURE AND OPERATION – Turbocharger Control System

3.1 General description
• In the turbocharger control system, various engine-related information (engine speed, coolant temperature, accelerator position) and driving status are collected by the relevant sensors and are sent to the engine electronic control unit and turbocharger electronic drive unit which then control the engine based on the information received.
• The turbocharger actuator controls the opening of turbine vanes according to control signals to ensure low fuel consumption and high torque operation over the entire speed range.

3.2 Electronic control system
(1) System block diagram

(2) Turbocharger control function
• In response to output data from various sensors, the engine electronic control unit determines the opening of turbine vanes as required by the engine operating status and sends necessary control signals to the turbocharger electronic drive unit. (Target opening of turbine vanes.)
• The turbocharger electronic drive unit activates the turbocharger actuator motor to detect the amount of resultant shaft position by means of the position sensor and sends it to the engine electronic control unit. (Actual opening of turbine vanes.)
Thus, the target opening of turbine vanes can be accurately maintained as commanded by the engine electronic control unit.

(2.1) Turbocharger actuator
• In response to command signals from the turbocharger electronic drive unit, the turbocharger actuator moves the shaft up and down by means of its DC motor to open and close the turbine vanes.

(3) Fault diagnosis function
• The engine electronic control unit continuously monitors the electronic drive units and sensors for faults. In the event that the engine electronic control unit finds a component faulty, it causes an indication to be made in the meter cluster to alert the driver. At the same time, it memorizes the fault location in the form of a diagnosis code and starts a control during fault.
• While the engine is running, the turbocharger electronic drive unit continuously monitor communication with the position sensor and motor of the turbocharger actuator communication with the engine electronic control unit. In the event that they identify a fault, they send fault data to the engine electronic control unit.
• While control necessitated by a fault is taking place, the system’s functionality is limited to ensure vehicle and driver safety. It is possible to read the memorized diagnosis code using a Multi-Use Tester or from flashing of the warning lamp.
• The control during fault recovers by servicing the faults. However, for some diagnosis codes, the warning lamp stays illuminated until the normal signals are input for several times.
• Diagnosis codes shown by the Multi-Use Tester and those indicated by flashing of the warning lamp are different.
• The Multi-Use Tester is capable of showing more detailed diagnosis codes.

3.3 Electronic control unit wiring diagram

 

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