The relays T6 and T7 in the engine compartment unit B1 manage the switching on of the fan N11 at two speeds: their coils are supplied by the ignition-controlled line (15/54), while the power lines are protected by the fuses F6 and F7, of the engine compartment unit B1 .Both are energized by a control signal - earth - coming from the engine control unit M10 .If the coolant reaches a higher temperature level, or the fan linear sensor K120 indicates to the control unit M10 - pin 54 of connector B - that the first pressure level has been reached, the control unit M10 sends a signal - from pin 14 of connector A - to the fan 1st speed relay T6, which sends the supply directly to the fan N11 via additional resistance O10: the fan then turns at the first speed (low).If the coolant reaches a higher temperature level, or indicates to the control unit M10 that a higher pressure has been reached, the control unit M10 sends a signal - from pin 30 of connector A - to the fan 2nd speed relay T7, which sends the supply directly to the fan N11 : the fan then turns at the maximum speed.Linear sensor K120 receives a power supply and reference earth from the engine management control unit M10 , pins 53 and 5 of connector A.