The main injection relay T9 of B1, energized by an (earth) signal coming from pin 62 of connector A of control unit M10, sends a power supply to thermostat N86 via the line protected by fuse F11 of B1.The thermostat N86 then regulates the temperture of the engine coolant depending on given parameters, managed by the engine management control unit M10 (engine speed, load conditions, gear engaged and outside temperature) and is controlled by a signal from pin 4 of connector B of M10.The coolant temperature sensor on the radiator hose K036A manages the electrically controlled thermostat: it receives a reference earth and sends a temperature signal to the engine management control unit M10 to pin 3 and pin 28 respectively of connector A of the engine management control unit M10.The engine coolant temperature sensor on thermostat K36B receives a reference earth and sends a temperature signal to engine control unit M10, to pins 25 and 60 of connector B respectively.If the opening of the thermostat is not sufficient, the activation of the engine cooling fans is required.The relay J30, located on the fan duct, manages the engagement of the fans N11 and N12 at the first speed: the coil and the power line are supplied by the line protected by fuse F6 of the engine compartment junction unit B1.If the engine coolant reaches an initial temperature level, measured by the two sensors K36, or the linear sensor K120 signals to the control unit M10 - pin 56 of connector A - that a certain pressure level has been reached, then the control unit M10 sends a signal - from pin 59 of connector A - which energizes the relay J30, which sends the power supply to the fans N11 and N12 via the additional resistances O10 and O12: the two fans turn together at the first speed (slow).The linear sensor K120 receives a power supply and reference earth from the engine management control unit M10, pin 39 and 23 of connector A.Relays T6 and T7 of the engine compartment junction unit B1 manage the switching on of the two speed fan N11: the coil power lines are protected by fuses F6 and F7 , also in engine compartment junction unit B1 .If the engine coolant reaches a higher temperature level, or the linear sensor K120 signals to the control unit M10 - pin 56 of connector A - that a higher pressure level has been reached, then the control unit M10 sends a signal - from pin 10 of connector A - which energizes the two relays T6 and T7 which send the power supply directly to the fans N11 and N12 which turn together at the maximum speed.