Switches
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| Illustration 1 | g02751683 |
(1) Key Switch (2) Parking brake Switch | |
Key Start Switch
The switch is located in the left instrument cluster. Refer to figure 1.
The switch is a rotary key switch. The START position is a momentary position.
The switch tells the ECM that the operator wants to start the engine. When the switch is in the START position, the circuit is closed. This event applies a +battery voltage to pin J2-1 (wire 307-OR) of the ECM. If the seat switch and the armrest switch are actuated, the ECM will turn on the output for the start relay.
Note: On machines that are equipped with the machine security system (MSS), the output for the start relay goes to the MSS. The MSS will then send an output to the start relay.
Parking Brake Switch
The switch is located on the left instrument cluster to the left of the key start switch. Refer to figure 1.
The switch tells the ECM that the operator wants to release the parking brake and the operator wants to enable the hydraulics
The switch is a momentary, rocker switch. When the switch is pressed, pin J2-53 (wire F780-PK) is grounded and pin J2-54 (wire A314-OR) is open.
While the parking brake is engaged, the hystat transmission will remain in NEUTRAL regardless of joystick position. If the machine is traveling while the parking brake is set, the machine controller will bring the machine to a stop and engage the parking brake. When the operator releases the parking brake, the hystat transmission will remain in NEUTRAL until the operator commands movement.
Arm Bar Switch
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| Illustration 2 | g02751856 |
(1) Armbar Switch | |
The switch is located on the left side of the armrest at the pivot point.
The switch tells the ECM the position of the armrest. The switch is a proximity switch with contacts that are normally open and normally closed. When the armrest is lowered, the normally closed contacts open and the normally open contacts close.
The normally open contacts are in series with the seat switch. The seat switch and the armrest switch create a circuit. When both the normally open contacts for the armrest and the seat switch are closed, pin J2-58 (wire G985-PU) of the ECM will be grounded. The armrest switch will also place an open input on pin J1-33 (wire G984-PK) of the ECM. When this event occurs, the operator is in the seat and the armrest is lowered.
Seat Switch
The switch is located within the operator seat. The connector for the switch is located beneath the seat.
The switch tells the ECM that the operator is in the seat. The switch is a momentary, normally open switch. When the seat is occupied, the switch is closed.
The seat switch is in series with the armrest switch. When both the normally open contact for the armrest and the seat switch are closed, pin J2-58 (wire G985-PU) of the ECM will be grounded. If the armrest is down, and the seat becomes unoccupied, the ECM will wait for 3 seconds before the operator is considered not present.
If the inputs are invalid, the operator will be considered not present, and the indicator will be illuminated.
Hydraulic Lockout Switch and Interlock Override Switch
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| Illustration 3 | g02751904 |
(1) Hydraulic Lockout and Interlock Override Switch | |
The switch for the hydraulic lockout and interlock override is located on the left overhead control panel. The interlock override and the hydraulic lockout share the same switch on the machine.
Depress the top of the switch in order to activate the hydraulic lockout.
The switch tells the machine ECM that the operator wants to disable the hydraulic system.
When the switch is actuated, an open is placed on pin J1-42 (wire E918-GN) and a ground is placed on pin J1-43 (wire E917-WH) of the machine ECM. The hydraulic system will be disabled.
The machine ECM monitors the status of the switch.
Depress the bottom of the switch in order to activate the interlock override.
The switch tells the ECM that the operator wants to be able to raise the armrest in order to exit the seat while the continuous flow function is active to operate an attachment such as a backhoe.
Pressing the switch puts a ground on the pin J2-55 (wire G982-PK) of the ECM.
The machine ECM monitors the status of the switch. If the input is grounded for 30 seconds or more, the ECM will interpret the signal as a stuck switch and the ECM will produce a diagnostic code.
Hydraulic Lockout Switch (Door)
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| Illustration 4 | g02753560 |
View from the operators seat. (1) Hydraulic Lockout Switch (2) Left Joystick | |
The switch is located near the center of the door by the wiper motor.
The switch tells the ECM to disable the hydraulics. However, it will not lock out the implements if the interlock override feature is enabled.
The switch is a two position limit switch. When the switch is not actuated, the normally closed contacts complete the circuit to the hydraulic lockout indicator. When the switch is actuated, the normally open contacts complete the circuit from the hydraulic lockout switch to pin J2-37 wire G943-BU of the ECM.
Multifunction Switch
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| Illustration 5 | g02751956 |
(1) Multi-Function Switch | |
The multifunction switch is located in the upper left-hand portion of the cab.
This switch allows the operator to toggle the function of the trigger on the left-hand joystick between Two Speed and the Auxiliary Electrical Function "AUX 7". The switch is located on the left overhead control panel.
Two Speed
| Two Speed - Push the top of the switch in order to use the trigger for the two speed control. Press the trigger and release the trigger on the front of the left-hand joystick in order to activate rabbit mode. In order to return to single speed, press the trigger and release the trigger again. |
Auxiliary Electrical Function "AUX 7"
| Auxiliary Electrical Function "AUX 7" - Push the bottom of the switch in order to activate the seventh auxiliary electrical function. Pull the trigger and hold the trigger on the left-hand joystick in order to provide electrical power to pin (B) on the connector for the work tool on the loader arm. Release the trigger in order to deactivate the control. |
Two-Speed Switch
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| Illustration 6 | g02752016 |
LH Joystick | |
The switch is located on the front side of the LH Joystick. The two speed switch is a momentary trigger switch.
The switch tells the ECM that the operator wants to energize the two speed function. In order to activate rabbit mode, the Multifunction Switch must also be in the Two Speed position.
The switch is a momentary, normally open switch. When the switch is actuated, a ground is placed on J2-46 (wire P982-BU) of the ECM.
The ECM monitors the status of the switch.
Continuous Flow Switch
The continuous flow switch is mounted in the LH joystick. Refer to figure 6
The continuous flow switch tells the machine ECM that the operator wants to supply a flow of hydraulic oil to the auxiliary circuit without the need to continuously hold the auxiliary hydraulic control.
In order to enable the system, use the primary auxiliary hydraulic input in order to achieve the desired hydraulic flow rate to the tool. When the tool is rotating at the desired speed, press and release the continuous flow switch. The auxiliary hydraulic input must be returned to neutral in order for the continuous flow feature to be able to take over control. If the auxiliary hydraulic control is not released within one second of releasing the continuous flow control, the continuous flow function will not be activated.
In order to disable the continuous flow feature, push either the auxiliary hydraulic control or push the continuous flow switch. Manual flow control to the auxiliary circuit is resumed.
The switch is a momentary, normally open push-button switch. When the switch is closed, the circuit puts a ground on pin J1-34 (wire P993-OR) of the ECM.
Auxiliary Hydraulic Control
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| Illustration 7 | g02752040 |
RH Joystick | |
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| Illustration 8 | g01356218 |
Schematic for the RH Joystick Handle | |
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| Illustration 9 | g01381044 |
Schematic for the Optional RH Joystick Handle | |
The auxiliary hydraulic control position sensor is located within the right-hand joystick.
This control provides hydraulic oil flow to the auxiliary connections on the loader arm. Engage the control in order to provide hydraulic oil flow to the high flow work tools.
The auxiliary hydraulic control is the thumb wheel on the work tool control (RH Joystick) that can be pressed upward or downward. The auxiliary hydraulic control tells the ECM that the operator wants to activate the auxiliary hydraulics. The auxiliary hydraulic control will allow the operator to control the amount of hydraulic oil flow that is sent to the auxiliary hydraulics.
The auxiliary hydraulic control sends a proportional signal to the auxiliary Machine ECM. The signal is a pulse width modulated signal (PWM) that is generated at a frequency between 500 Hz ± 80 Hz. When the auxiliary hydraulic control is in the neutral position, a duty cycle of 50% ±3% is seen by the ECM. When the auxiliary hydraulic control is pressed up or down, the duty cycle will vary from 50% to a minimum of 20% in the A1 position (down) and from 50% to a maximum of 80% in the A2 position (up).
The Machine ECM receives the proportional signal on pin J2-25 of the ECM. The auxiliary hydraulic ECM will then send a proportional signal to the corresponding modulated valve (auxiliary) (A1 or A2).
Holding the right-hand joystick trigger for 3 seconds sets the "target work tool angle" for the self level system when the self level feature is active and the joystick is in the neutral position.
While the right-hand joystick is in the rack or dump position, the trigger grounds wire A771 coming from the machine ECM pin J2-30. This overrides the tilt command and drive the bucket to the default operator angle.
The ECM monitors the auxiliary control for duty cycles that are erratic, out of range or an abnormal frequency. A diagnostic code will then be set and the auxiliary hydraulics will not function.
Creep Control Switch
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| Illustration 10 | g02752043 |
(1) Creep Control Switch (2) Ride Control Switch | |
The creep control switch is located in the upper right-hand portion of the cab.
The creep control feature is used to adjust the maximum speed of the machine for using different work tools for performing specific operations. The creep allows for precise slow speed travel at high engine speed to maintain full auxiliary flow to the work tool. The creep control switch is a two position switch. When the switch is in the OFF position, the creep control system is off. When the switch is in the ON position, the creep control system will be on and the indicator will be illuminated. The machine must be in NEUTRAL in order to change from a non-creep mode to creep mode and back to non-creep mode. When a diagnostic is present on the switch, the current state of the switch will be held by the ECM.
Ride Control Switch
The ride control switch is located in the upper right-hand portion of the cab. Refer to figure 10
The ride control feature allows the lift arm cylinders to act as shock absorbers to improve the ride over rough terrain. The ride control switch is a two position switch. When the switch is in the OFF position, the ride control system is off. When the switch is in the ON position, the ride control system will activate when the motor speed of the machine exceeds the activation speed for the ride control feature. When the ride control system is active, the ECM energizes the ride control relay. The relay then energizes the ride control solenoids which isolate the ride control accumulator from charge oil, open the lift cylinder rod ends to tank, and open the lift cylinder head ends to the ride control accumulator. The ride control system will turn OFF when the average motor speed drops below the deactivation threshold or when the bucket dump solenoid is energized.
Air Filter Switch
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| Illustration 11 | g02753457 |
View into the engine compartment with the radiator removed (1) Air Filter Switch | |
The air filter switch is located on top of the cannister in the right-hand portion of the engine compartment.
The air filter switch will close, if the air filter is blocked with debris. This switch is normally open. A warning will be displayed on the monitor. However, when a warning of higher priority is occurring at the same time, the warning with the higher priority will be displayed.
Hydraulic Filter Bypass Switch
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| Illustration 12 | g02753477 |
The contacts of the switch are normally open below the deactuation pressure. If the pressure goes above the actuation pressure, the hydraulic return oil bypasses the filter. When the switch closes, a voltage signal is sent to the ECM. This notifies the ECM of the plugged hydraulic filter. Once the pressure drops below the deactuation pressure, the switch opens. The filter is functioning properly when the switch opens.
Sensors
Left and Right Motor Speed Sensors
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| Illustration 13 | g02758477 |
272D Speed Sensor The speed sensor on a 272D is located under the cab in the belly of the machine. The left and right speed sensors are located in mirror positions to each other on each side of the machine. (1) Left Motor Speed Sensor | |
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| Illustration 14 | g02758497 |
299D Speed Sensor The speed sensor on a 299D is located on the back of the drive motor between the tracks and the machine hull. The left and right speed sensors are located in mirror positions to each other on each side of the machine. (1) Motor Speed Sensor. | |
The left motor speed sensor allows the ECM to determine the actual speed of the left hydraulic motor. The sensor provides two square wave signals that are proportional to the speed of the motor. The signals are used to calculate the speed and direction of the left motor. This sensor is powered by the regulated 8 VDC power supply on the Machine ECM.
Right Motor Speed Sensor
Refer to Figure 13.
The right motor speed sensor allows the ECM to determine the actual speed of the right hydraulic motor. The sensor provides two square wave signals that are proportional to the speed of the motor. The signals are used to calculate the speed and direction of the right motor. This sensor is powered by the regulated 8 VDC power supply on the Machine ECM.
Throttle Position Sensor
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| Illustration 15 | g02752056 |
(1) Engine Speed Control Knob | |
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| Illustration 16 | g02752057 |
(2) Engine Speed Control Pedal | |
There are two throttle position sensors. One is in the pedal, the other in the hand dial. Both sensors work together for the throttle arbitration feature.
The throttle position sensor controls the maximum machine speed. The sensor also determines the desired engine speed for a certain position of the pedal. The throttle position sensor provides a PWM signal proportional to the position of the throttle pedal. The duty cycle increases as the pedal is depressed. When the hand dial is in the full clockwise position, the pedal becomes a deceleration pedal and the duty cycle will decrease as the pedal is depressed.
Hydraulic Oil Temperature Sensor
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| Illustration 17 | g02753377 |
View underneath the belly plate. (1) Hydraulic Tank (2) Hydraulic Oil Temperature Sensor | |
The hydraulic oil temp sensor is located beneath the hydraulic tank.
The hydraulic oil temperature sensor allows the ECM to determine the temperature of the hydraulic oil. The sensor sends a signal to the ECM. The temperature is limited from -40 °C (-40.0000 °F) to 120 °C (248 °F).
Fuel Level Sensor
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| Illustration 18 | g02752077 |
(1) Fuel Level Sensor | |
The fuel level sensor is located on top of the hydraulic tank.
The ECM reads the fuel level signal. The sensor is a passive analog sensor that provides a voltage signal to the ECM. If the signal is within the range of 0.25 VDC and 4.95 VDC, the ECM compares the voltage against predetermined software parameters in order to provide the fuel level percentage.
Self Level Limit Switch
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| Illustration 19 | g02752096 |
(1) Self Level Limit Switch | |
The limit switch is located on the inside surface of the lift arms, close to the right tower.
The switch is a magnetic switch that detects the proximity of a pair of ferrous metal targets mounted to the lift arm linkage.
If these two targets are not adjusted properly, they may damage the switch or cause problems with the self level calibration, the self level feature, the return-to-dig feature, or the lift snubbing feature. When the lift arms are positioned so that one of the metal targets is next to the limit switch, there should be a 10mm gap between the sensor and the target. This applies to both targets.
The Limit switch signal will be monitored to provide lift arm position logic to the Machine ECM and allow for lift cylinder snubbing near the upper and lower lift arm travel limits. The switch is a proximity switch with contacts that are normally open and normally closed. When the lift arm is within the specified proximity of the target, the normally closed contacts open and the normally open contacts close.
When the switch is in range of the target the N/O contact is closed and pin J1-26 of the ECM, (wire T867) is shorted to ground. When the switch is NOT in range of the target the N/C contact is closed and pin J2-47 on the ECM (wire T868) is shorted to ground.
Self Level Inclinometer
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| Illustration 20 | g02752116 |
(1) Inclinometer | |
The inclinometer is located on the rear, right-hand side of the coupler.
The Inclinometer sends a PWM signal to the ECM on pin J2-15 (wire A426). The PWM signal represents the operating angle of the bucket. The self-level feature uses this input to maintain bucket position while raising and lowering the lift arms and to find the "target work tool angle" in Return to Dig and Work Tool Positioner modes.
Lift Cylinder Pressure Sensor
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| Illustration 21 | g02752121 |
(1) Lift Cylinder Pressure Sensor | |
The Lift Cylinder Pressure Sensor is located on the front of the firewall and to the right of the Implement Valve. The Lift Cylinder Pressure Sensor allows the Self level system to make adjustments to compensate for varying loads.
The sensor is a PWM sensor that sends a signal to the ECM on pin J2-17 (wire E416). The Self-Level Feature uses this input to monitor head end pressure on the lift cylinder.