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| Illustration 1 | g03409367 |
Propel Electrical Schematic (1) From display/keypad fuse (2) From propel/steer fuse (3) From engine main fuse (4) From machine ECM 1 fuse (5) Machine ECM number one (6) Parking brake switch (7) Keypad (8) Propel lever (9) Display (10) Engine ECM (11) CAN resistor "1" (12) CAN resistor "2" (13) Back up alarm relay (14) Back up alarm (15) Propel reverse solenoid (16) Propel forward solenoid (17) Shift solenoid (18) Interlock valve solenoid (19) RH front drum speed sensor (20) LH rear drum speed sensor | |
Power Distribution
When the electrical disconnect switch is in the ON position, power transfers from engine main fuse (3) to the following terminals of engine ECM (10) : "J1-7", "J1-8", "J1-15" and "J1-16". This voltage provides the main power source for the engine ECM. The engine ECM is grounded at the following terminals: "J1-1", "J1-2", "J1-3", "J1-9" and "J1-10".
When the engine start switch is in the ON position, the machine ECM "1" fuse (4) is energized. Power transfers from machine ECM "1" fuse to the following terminals of machine ECM number one (5) : "2", "47", "48", "49" and "50". This voltage provides the main power source for the machine ECM number one and also provides the wake-up signal. The machine ECM number one is grounded at terminal "1".
When the engine start switch is in the ON position and the machine main power relay is energized, power transfers to the display/keypad fuse. Power transfers from display/keypad fuse (1) to the following locations:
- Contact "1" and contact "5" of keypad (7)
- Contact "2" of display (9)
When the engine start switch is in the ON position and the machine main relay is energized, power transfers to propel/steer fuse (2). Power transfers from the propel/steer fuse to the following locations:
- Contact "2" of propel lever (8)
- Contact "5" of parking brake switch (6)
- Contact "30" and contact "86" of backup alarm relay (13)
CAN Communication
Keypad (7), propel lever (8), display (9), engine ECM (10) and machine ECM number one (5) communicate through a CAN.
In order to prevent data loss in the communication lines, termination resistors are required at the ends of the CAN bus. CAN resistors (11) and (12) act as termination resistors. 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.
Parking Brake Control
Machine ECM number one (5) monitors the circuits at terminal "6" and terminal "7" in order to determine the condition of parking brake switch (6). When terminal "6" is closed and terminal "7" is open, the parking brake switch is determined to be in the OFF position. When terminal "6" is open and terminal "7" is closed, the parking brake switch is determined to be in the ON position. If the circuits at these two terminals are simultaneously open or closed, the machine ECM number one generates a level-three fault.
Machine ECM number one (5) controls interlock valve solenoid (18) with a digital output signal from terminal "41". When the machine ECM number one determines that the parking brake should be engaged, no signal is generated. When the machine ECM number one determines that the parking brake should be released, a signal is generated.
If parking brake switch (6) is in the ON position, the parking brake is engaged, regardless of the position of propel lever (8) .
Desired Speed and Direction
Machine ECM number one (5) controls machine propel using open loop logic. The ECM monitors input from the following components in order to determine the desired speed and direction:
- Propel lever (8)
- Increase speed button and decrease speed button on keypad (7)
- Propel mode button on keypad (7)
Machine ECM number one (5) monitors the position of propel lever (8) through the CAN. The machine ECM number one assigns a value to each position of the propel lever. The values range from 100 percent to 100 percent.
Machine ECM number one (5) monitors input from the increase speed switch and from the decrease speed switch through the CAN. The ECM assigns a scale factor from zero percent to 100 percent depending upon the number of times the switches have been actuated.
Machine ECM number one (5) monitors input from the propel mode switch through the CAN. The ECM toggles between low and high with each actuation of the switch. The software in the machine ECM number one contains a speed map for each propel mode.
In order to determine the desired direction of travel, machine ECM number one (5) evaluates the value assigned to the position of propel lever (8). 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. The +100 percent value is assigned to the FULL FORWARD position.
In order to determine the desired machine speed, machine ECM number one (5) scales the input from propel lever (8). A scale factor and speed map are then used by the ECM software to calculate the desired speed.
Once the desired speed and direction have been determined, machine ECM number one (5) generates an output signal to the appropriate pump control solenoids.
Shift Control
Machine ECM number one (5) uses the input from the propel mode switch in order to control shift solenoid (17). When the propel mode is set to low, the ECM does nothing. When the propel mode is set to high, the machine ECM number one generates a digital output signal from terminal "33" to the shift solenoid.
Back-up Alarm Control
When the propel lever is in the reverse range, machine ECM number one (5) sends a backup alarm request to engine ECM (10). The engine ECM generates a signal from contact "17" and energizes the coil of backup alarm relay (13). In this case, the backup alarm relay closes and transfers power from propel/steer fuse (2) to back up alarm (14) .
Uncommanded Movement Detection
Machine ECM number one (5) is programmed to detect uncommanded machine movement. When the actual ground speed is greater than 1.5 km/hr (0.9 mph), this logic will stop machine movement under the following conditions:
- The actual ground speed is a specified amount higher than the commanded speed for a duration of time. The default speed differential is set at 20 percent. The default time is set at 250 ms.
- The actual machine direction is opposite the commanded direction for a specified amount of time.
If machine ECM number one (5) detects uncommanded movement, the system generates a level-three fault. During an active uncommanded movement fault, the machine ECM number one disables the propel system and the vibratory system.
Machine ECM number one (5) monitors input from right front speed sensor (19). Display (9) monitors input from left rear speed sensor (20) and transmits this information to the machine ECM number one via CAN lines. The machine ECM number one uses the inputs from these two speed sensors in order to determine the actual machine speed and direction. Contact "1" of each speed sensor receives an 8 V power supply signal from terminal "8" of the machine ECM number one. Contact "2" of both sensors are grounded at a common 8 V sensor return at terminal "9" of the machine ECM number one.
Each speed sensor provides two pulsed input signals. Contact "4" of left rear speed sensor (20) provides an input signal to terminal "10" of display (9). Contact "3" of the left rear speed sensor provides an input signal to terminal "11" of the display. Contact "4" of right front speed sensor (19) provides an input signal to terminal "19" of machine ECM number one (5). Contact "3" of the right front speed sensor provides an input signal to terminal "18" of the machine ECM number one.
Machine ECM number one (5) compares the frequency of the two signals from left rear speed sensor (20). The ECM also compares the frequency of the two input signals form right front speed sensor (19). If internal signals from either sensor are out of sync, the machine ECM number one generates a level-two fault. In this case, the ECM sets the propel mode to low, and the undetected movement detection logic and the vibratory system are disabled.
Machine ECM number one (5) averages the input from the two sensors to calculate the machine speed. The machine ECM number one compares the observed machine speed to the desired machine speed.