Functional Description

Functional Description

The engine control unit S11 controls and adjusts the entire electronic injection and ignition system.

The control unit receives the key-operated supply at pin 13 of connector B from the line protected by fuse F14 of fusebox G1.

Relay S41 controls the system supply: it is supplied from the battery, by the line of fuse S36. The enable signal from pin 46 of connector C of the control unit S11 energises relay S41 and sends the supply to the control unit itself, at pins 7, 8 and 1 of connector A (the line that leads from S41 to pin 1 is also protected by wander fuse S46).

The pump relay S12a is also supplied from the battery, by the line of fuse S36: the signals that energise the pump relay S12a, which supplies the electric fuel pump F18 lead from pins 30 and 52 of connector C of the control unit. The fuel pump is connected to an inertial switch H20, which in the event of a crash cuts off the circuit, thereby stopping the dangerous flow of fuel.

In case of intervention on switch H20, the relative telltale light on the panel C10 is also turned on.

The control unit N6 controls glow plug warming A13: this is supplied directly by the battery through the line protected by fuse G352. It receives the commands from pin 38 and 51 of connector C of S11 and sends a feedback signal to pin 1 of connector B of the control unit.

Pins 4, 5 and 6 of connector A of S11 are earthed.

The control unit receives the signals from the different sensors, thereby keeping all the engine operating parameters under control.

The rpm sensor S31 supplies information about the engine speed, through a frequency signal sent to pin 26 of connector D of the control unit S11. From pin 37 of connector D of the control unit it receives an earth signal. Both signals are weak in intensity and are, therefore, suitably screened.

The timing sensor S13 is supplied from pin 12 of connector D of S11. It receives a reference earth signal from pin 2 of connector D of the control unit to which it sends a frequency signal at pin 3 of the same connector.

The engine temperature transmitter L7, receives a reference earth from pin 27 of connector D of the control unit, and supplies a signal proportionate with the temperature of the engine fluid to pin 36 of the same connector.

The air flow meter S5 receives the main supply from pin 11 of connector D of the control unit and a reference voltage from pin 1 of the same connector. To pin 14 of connector D it sends a signal proportionate with the flow of air. Inside S5 there is also an air temperature sensor: the reference earth of the sensor is supplied by pin 4 of connector D of S11, while pin 23 of the same connector receives the air temperature signal.

The accelerator pedal L49 is fitted with two integrated potentiometers (a main one and and a safety one). The main one receives the supply and earth respectively from pin 5 and 23 of connector C of S11 and sends the corresponding signal to pin 10 of the same connector. The other one receives the supply and earth respectively from pin 21 and 8 of connector C and it sends the signal to pin 9 of connector C of S11.

The fuel temperature sensor L51, fitted on the return manifold, detects the temperature of the fuel oil leaving the injectors. It receives a reference earth from pin 1 of connector C of S11 and sends the fuel temperature signal to pin 24 of the same connector.

The supercharging sensor L36 detects the turbo charger (activated) pressure. It is supplied from pin 8 of connector D of S11 and receives a reference earth from pin 7 of the same connector. The signal is sent to pin 6 of connector D of the control unit itself.

The fuel pressure sensor L59 has the task of sending the injection control unit a feedback signal for regulating the pressure and length of injection. It receives the supply and the reference earth respectively from pin 13 and 34 of connector D of S11; then it sends the pressure signal to pin 24 of the same connector.

The task of the fuel pressure regulator M28 is to keep the pressure of the fuel in the accumulator constant. The two command signals lead from pin 31 and 21 of connector D of the control unit.

The EGR solenoid valve L46 controls exhaust gas recirculation- It is supplied by pin 37 of connector C of S11 and sends a signal to pin 50 of the same connector.

Pin 8 of connector C of S11 receives the signal leading from the brake light switch H3, which receives the "key-operated" supply from fuse F15 of fusebox G1.

Pin 2 of connector C of S11 receives the signal leading from the clutch pedal switch H21, which also receives the "key-operated" supply from fuse F15.

The injectors S50 receive the supply to enable opening from pin 2 (cylinders 1 and 4) and 4 (cylinders 2 and 3) of connector E of S11.

The engine control unit sends the commands to the injectors from pin 9, 7, 5 and 3 of connector E, respectively for cylinders 1, 2, 3 and 4.

When the instrument cluster C10 receives (pin 15 of connector B) the earth signal from pin 48 of connector C of S11, it turns on the "injection failure" warning light"; in the same way at pin 8 of connector A of C10, when the earth signal reaches pin 43 of connector C, the "glow plug warming" warning light turns on.