ENGINE AR-COMPLETE 1695229 - Caterpillar

Illustration 1 g02907445
Fan Electrical Schematic (1) B+ from machine fuse (2) B+ from engine ECM fuse (3) ATAAC air temperature sensor (4) Hydraulic oil temperature sensor (5) Engine ECM (6) Fan solenoid (7) Engine coolant temperature sensorWhen the electrical disconnect switch is in the ON position, power transfers from engine ECM fuse (2) to engine ECM (5). This voltage provides the main power source for the engine ECM. When the start switch is in the ON position, power transfers from machine fuse (1) to terminal "J1-70" of engine ECM (5). This voltage provides the wake-up signal to the engine ECM.When engine ECM (5) is active, the ECM monitors the hydraulic oil temperature, the engine coolant temperature, and the ATAAC air temperature.Hydraulic oil temperature sensor (4) is a resistance type sensor. Engine ECM (5) passively monitors input from this sensor at terminal "J1-16". The hydraulic oil temperature sensor is grounded at terminal "J1-3" of the engine ECM. Software in the engine ECM converts the signal at terminal "J1-16" into a temperature value.Engine coolant temperature sensor (7) is a resistance type sensor. Engine ECM (5) passively monitors input from this sensor at terminal "J2-43". The engine coolant temperature sensor is grounded at terminal "J2-37" of the engine ECM. Software in the engine ECM converts the signal at terminal "J2-43" into a temperature value.ATACC air temperature sensor (3) is a resistance type sensor. Engine ECM (5) passively monitors input from this sensor at terminal "J1-24". The intake manifold temperature sensor is grounded at terminal "J1-3" of the engine ECM. Software in the engine ECM converts the signal at terminal "J1-24" into a temperature value.Engine ECM (5) evaluates the input signals from the above sensors in order to determine the output signal to send to fan solenoid (6). The engine ECM sends this signal from terminal "J1-43" to contact "1" of the fan solenoid. Contact "2" of the fan solenoid is grounded at terminal "J1-51" of the engine ECM. The greater the output signal, the slower the speed of the fan. The minimum and maximum solenoid currents are adjusted with the ET software.