Control unit M010 receives engine coolant data measured by dedicated sensor K036 via pins 85 84 and 86 85 of connector B.On the basis of input data and stored parameters, engine management unit M010 determines whether to activate the high or low speed setting of engine cooling fans N011 and N012.The control unit controls the low speed of engine fan N012 only from pin 20 of connector A. The unit supplies an earth signal to excite relay coil T06. The power supply reaches fan N012 via resistance load O010, which reduces the current.Engine management unit M010 controls the low speed of both engine fans N011 and N012 from pin 19 of connector A. It supplies an earth signal to excite the coil of relay T07 and a direct power supply from the battery is supplied to fan N012. Simultaneously, relay J028 closes its internal contact to supply supplementary fan N011.The high and low speed supply lines are protected respectively by F07 and F06 housed in engine bay junction unit B001.