Power Distribution
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| Illustration 1 | g03325580 |
Cooling Fan Electrical Circuit (1) From C3.4 engine actuator use (2) From C3.4 engine ECM "one" fuse (3) From C3.4 engine ECM "two" fuse (4) From propel and steer fuse (5) From machine fuse (6) Engine coolant temperature sensor (7) Engine ECM (8) Hydraulic oil temperature sensor (9) Machine ECM number "one" (10) ATAAC air temperature sensor (11) CAN resistor "1 " (12) Fan solenoid | |
When the main power relay is energized, power delivered to the following locations in the fan system:
- C3.4 engine actuator fuse
- C3.4 engine ECM "one" fuse
- C3.4 engine ECM "two" fuse
- Propel and steer fuse
- Machine fuse
Power transfers from propel and steer fuse (4) to terminal "J1-54" of engine ECM (7). This voltage provides the wake-up signal to the ECM.
Power transfers from the C3.4 engine ECM "one" fuse (2) to terminal "J1-1" of engine ECM (7).
Power transfers from the C3.4 engine ECM "two" fuse (3) to terminal "J1-3" and "J1-5" of engine ECM (7). This voltage provides the main power source for the engine ECM.
Power transfers from machine fuse (5) to terminal "2", terminal "47", terminal "48", terminal "49" and terminal "50" of machine ECM number "one" (9). This voltage provides the main power source for the ECM.
CAN Communication
The CAN lines provide high speed communication between machine ECM number "one" (9) and the engine ECM (7). The CAN requires a positive line and a negative line. The positive line is connected to terminal "3" of machine ECM number "one". The negative line is connected to terminal "4" of machine ECM number "one".The positive line is connected to terminal "J1-46" of the engine ECM. The negative line is connected to terminal "J1-47" of the engine ECM.
In order to prevent data loss in the communication lines, termination resistors are required at the ends of the CAN bus. CAN resistor "1" (11) acts as a termination resistor. The CAN resistor absorb unwanted noise in the communication system which can result in abnormal machine operation.
Input to Machine ECM Number-One
Hydraulic oil temperature sensor (8) is a resistance type sensor. Machine ECM number "one" (9) passively monitors input from this sensor at terminal "29". The hydraulic oil temperature sensor is grounded at a frame ground. Software in the ECM converts the input signal received at terminal "29" of machine ECM number "one" into a temperature value.
ATAAC air temperature sensor (10) is a resistance type sensor. Machine ECM number "one" (9) passively monitors input from the ATAAC air temperature sensor at terminal "30". The ATAAC sensor is grounded at a frame ground. Software in the ECM converts the input signal received at terminal "30" of the machine ECM number "one" into a temperature value.
Input to the Engine ECM
Engine coolant temperature sensor (6) is a resistance type sensor. Engine ECM (7) passively monitors input from this sensor at terminal "J2-57". The engine coolant temperature sensor is grounded at terminal "J2-58" of the engine ECM. Software in the engine ECM converts the signal at terminal "J2-57" into a temperature value.
Fan Control
Machine ECM number "one" (9) transmits the value of the PWM signal to engine ECM (7) through the CAN lines.
Engine ECM (7) uses the signal information to vary the duty cycle of the PWM signal in order to approximate a specific DC voltage. The effective voltage that is sent to cooling fan solenoid (12) is proportional to the duty cycle. This effective voltage will determine the voltage drop across the fan solenoid. This voltage drop controls the amount of power transmitted to the fan solenoid.