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| Illustration 1 | g03277037 |
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Steering Electrical Schematic (1) C3.4 engine ECM fuse "1" (2) C3.4 engine ECM fuse "2" (3) B+ from propel and steering fuse (4) From machine ECM number one fuse (5) From display/keypad fuse (6) Hydraulic oil temperature sensor (7) Propel lever (8) Steering angle position sensor (9) Steering encoder (10) Seat position switch "2" (11) Seat position switch "1" (12) Steering shunt solenoid (13) Warm up valve solenoid (14) Front clockwise solenoid (15) Front counterclockwise solenoid (16) Machine ECM number one (17) Can Resistor 1 (18) Engine ECM | |
When the electrical disconnect switch is in the ON position, power is delivered to the key switch.
When the key switch is in the ON position, power is delivered to propel/steering fuse (3). Power transfers from this fuse to terminal "J1-54" of engine ECM (18). This voltage provides the wake-up signal to the engine ECM. Power transfers from the engine ECM through the engine main relay to the C3.4 engine ECM one fuse (1) and the C3.4 engine ECM fuse two (2).
Power from the C3.4 engine ECM one fuse (1) is delivered to terminal "J1-1" of the engine ECM. Power transfers from 3.4 engine ECM fuse two (2) to terminal "J1-3" and "J1-5" of engine ECM (18). This voltage provides the main power source for the engine ECM.
When the key switch is in the ON position, power transfers from machine fuse (4) to terminal "2", and "47" to "50" of machine ECM number one (16). This voltage provides the main power source for the machine ECM number one.
When the engine start switch is in the ON position and the machine main relay is energized, power transfers to display/keypad fuse (5). Power transfers from the display/keypad fuse to Contact "3" of seat position switch "2" (10).
When the engine start switch is in the ON position and the machine main relay is energized, power transfers to propel/steer fuse (3). Power transfers from the propel/steer fuse to the following locations:
- Contact "2" of propel lever (7)
- Contact "54" of engine ECM (18)
- Contact "3" of seat position switch "1" (11)
After engine ECM (18) and machine ECM number one (16) receives power, the ECMs begin to monitor the CAN bus. Propel lever (7), engine ECM and and machine ECM number one communicate through the CAN
In order to prevent data loss in the communication lines, termination resistors are required at the ends of the CAN bus. CAN resistor 1 (17) acts as a termination resistor. The CAN resistors absorb unwanted noise in the communication system which can result in abnormal machine operation.
Differences in materials along the CAN bus can cause data pulses in the bus to reflect back through the bus. This reflection, also known as "jitter", creates unwanted noise in the CAN bus. Jitter in the communication lines between computers can distort the original data signals. The distortion can result in data loss.
Data in the CAN bus can also be contaminated with radio frequency interference (RFI). This interference can be caused by a number of devices which operate on or near the machine. RFI creates noise in the communication lines which can also distort the original data signals and cause data loss.
Steering shunt solenoid (12) is energized when the steering system is enabled or when the warm-up valve is energized.
Steering shunt solenoid (12) enables and disables the steering system. When the steering shunt solenoid is energized, the steering shunt valve is closed and oil from the steering pump is routed to the steering control valve. In this case, the steering system is enabled. When the steering shunt solenoid is de energized, the steering shunt valve opens and hydraulic oil from the steering pump is sent directly to the hydraulic tank. In this case, the steering system is disabled. The steering shunt solenoid receives power from terminal "32" of machine ECM number one (16).
If the steering system detects motion without an active steering command, an uncommanded movement detection (UCMD) fault is logged and the steering system, propel system, and vibratory system will be disabled. If the steering system detects motion that is opposite the commanded direction, a UCMD fault is logged and the steering system, propel system, and vibratory system will be disabled.
The steering system is a closed loop system that is position controlled. Steering angle position sensor (8) measures the angle of machine articulation and transmits this information to terminal "25" of machine ECM number one (16).
Machine ECM number one (16) monitors the signals from the two steering sensors in steering encoder (9). The machine ECM number one counts the pulses in these signals and compares the phases of the signals in order to determine the position and direction of rotation of the steering wheel.
Steering is controlled by a solenoid controlled steering valve. Front clockwise solenoid (14) causes the machine to turn right. Front counterclockwise solenoid (15) causes the machine to turn left.
Machine ECM number one (16) monitors inputs from steering angle position sensor (8) and steering encoder (9). Based on these inputs, the machine ECM number one sends signals to front counterclockwise solenoid (15) and front clockwise solenoid (14).
Steering encoder (9) includes an electronically controlled friction device to control the force required to turn the steering wheel. Machine ECM number one (16) transmits a signal to control the friction device. This device applies a variable force to the steering wheel that causes the wheel to resist turning. The friction device is activated when the steering system is enabled. When the machine has reached the mechanical steering limit, the highest friction level is applied in order to lock the steering wheel. The friction level is proportional to the difference between the desired steering angle and the actual steering angle. The desired steering angle is determined by the steering encoder. The actual steering angle is determined by the steering angle position sensor. The friction level prevents the operator from turning the steering wheel faster than the machine can respond.
In order to determine the desired direction of travel, machine ECM number one (16) evaluates the value assigned to position of the propel lever. Negative values indicate reverse travel. Positive values indicate forward travel. A value of zero percent indicates that the propel lever is in the NEUTRAL position. The 100 percent value is assigned to the FULL REVERSE position of the lever, and the 100 percent value is assigned to the FULL FORWARD position.
Note: Travel direction is determined with respect to the direction the operator station is facing. When the operator station is facing the rear of the machine, the value assigned to the position of the propel lever is the opposite of what is assigned when the operator station is facing the front of the machine.
Hydraulic oil temperature sensor (6) monitors the temperature of the oil in the hydraulic tank and sends this information to the machine ECM number one (16). When the hydraulic oil temperature is less than
Warm up valve solenoid (13) controls hydraulic pressure in the steering manifold and raises pressure to the setpoint of the relief valve. When the warm-up valve solenoid is energized, hydraulic pressure increases to the setpoint of the steering relief valve. As hydraulic oil is forced through the relief valve, the oil is heated.