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| Illustration 1 | g01429393 |
Left Side of Machine (1) Circuit breaker for engine control | |
The circuit breaker for engine control (1) is located in a circuit breaker panel on the left side of the machine. The door on the left side of the machine provides access to this component.
The circuit breaker for engine control (1) is a manual reset circuit breaker. This circuit breaker is rated at 20 amp. The circuit breaker for engine control receives power from the main circuit breaker when the electrical disconnect switch is in the ON position. Power transfers from the circuit breaker for engine control to the following terminals on the engine ECM: terminal "J1-7", terminal "J1-8", terminal "J1-15" and terminal "J1-16".
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| Illustration 2 | g01429395 |
Compartment at Front of Operator Station (2) Circuit breaker for machine ECM (3) Override resistor for propulsion (right track) (4) Override resistor for propulsion (left track) (5) Circuit breaker for operator ECM (6) Circuit breaker for limp home mode (7) Circuit breaker for operator control | |
A circuit breaker panel is mounted to the door of the compartment at the front of the operator station. The compartment door provides access to these components. The circuit breaker panel contains the following circuit breakers, which are part of the control system for propulsion:
- Circuit breaker for machine ECM (2)
- Circuit breaker for operator ECM (5)
- Circuit breaker for limp home mode (6)
- Circuit breaker for operator control (7)
When the electrical disconnect switch is in the ON position, power from the main circuit breaker is available at the circuit breaker for operator control (5) and at the circuit breaker for machine ECM (2). When the main power relay is energized the power from the main circuit breaker is available at the circuit breaker for operator control (7) and at the circuit breaker for limp home mode (6).
The circuit breaker for machine ECM (2) is a manual reset breaker. This circuit breaker is rated at 20 amp. Power transfers from the circuit breaker to the following terminals on the machine ECM: terminal "J1-31", terminal "J1-39" and terminal "J1-47".
The override resistor for propulsion (3) that is on the right track and the override resistor for propulsion (4) that is on the left track will limit the speed at which the machine will operate when the override switches for the propulsion are used.
The circuit breaker for operator ECM (5) is a manual reset breaker. This circuit breaker is rated at 20 amp. Power transfers from this circuit breaker to the following terminals of the control unit for operator: terminal "J1-31", terminal "J1-39" and terminal "J1-47".
The circuit breaker for limp home mode (6) is a manual reset breaker. This circuit breaker is rated at 15 amp. Power transfers from the circuit breaker for limp home mode to the following locations:
- Contact "1" of propulsion override resistor (3) for the right track.
- Contact "1" of propulsion override resistor (4) for the left track.
- Contact "5" of the right override switch for propulsion.
- Contact "5" of the left override switch for propulsion.
- Terminal "J1-1" of the machine ECM
- Terminal "J2-1" of the machine ECM
The circuit breaker for operator control (7) is a manual reset breaker. This circuit breaker is rated at 15 amp. Power transfers from this circuit breaker to the indicator in the emergency stop switch and to contact "5" of the parking brake switch.
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| Illustration 3 | g01429397 |
Compartment at Front of Operator Station (8) Machine ECM (9) "J2" connector (10) "J1" connector | |
Machine ECM (8) is mounted to the door of the compartment at the front of the operator platform. The compartment door provides access to this component.
Machine ECM (8) controls the propulsion system. This ECM has two 70-pin connectors. Connector "J1" (10) and connector "J2" (9) receive input signals from components around the machine which monitor current machine operating conditions. The software for the system compares the gathered input to information which is stored in the ECM memory. The software evaluates the current conditions and the software generates an output signal in order to control the propulsion system within set parameters. The machine ECM uses closed loop logic in order to control machine propulsion and steering.
Note: Machine ECM (8) is programmed with self-diagnostic logic. Service information can be accessed by using the operator display on the machine or using Caterpillar Electronic Technician (ET).
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| Illustration 4 | g01429398 |
Connector "J1" for machine ECM | |
When the electrical disconnect switch is in the ON position, power transfers from the circuit breaker for the machine ECM to the following terminals of machine ECM (8) : terminal "J1-31", terminal "J1-39" and terminal "J1-47". This voltage input provides the power for the processor. When the main power relay is energized, power transfers from the circuit breaker for limp home mode to terminal "J1-1" of the machine ECM. This voltage input provides the wakeup signal to the machine ECM. The machine ECM is grounded at the following terminals: terminal "J1-13", terminal "J1-23" and terminal "J1-57"/
After machine ECM (9) has been activated, the ECM generates an 8 volt power output signal from terminal "J1-44". Power transfers from this terminal to the following locations:
- Contact "1" of the speed sensor on the right propulsion motor.
- Contact "1" of the speed sensor on the left propulsion motor.
- Contact "A" of the left sensor for decelerator.
- Contact "A" of the right sensor for decelerator.
Machine ECM (8) provides a ground path for the speed sensors and the sensors for the decelerator at terminal "J1-45". The machine ECM provides a ground path for the EDCs on the propulsion pumps at terminal "J1-50".
The machine ECM (8) and the operator control unit are externally identical. However due to the internal differences, the machine ECM has a different part number from the operator control unit. In order to prevent incorrect software installation, the harness configuration at each control unit provides a series of switch input signals. These signals identify the unit's function. The machine ECM is wired as the following:
- Terminal "J1-26" (ground)
- Terminal "J1-27" (open)
- Terminal "J1-28" (open)
- Terminal "J1-32" (ground)
Machine ECM (8) communicates with the other control units on the machine and with electronic service tools through the Cat Data Link. The Cat Data Link is a proprietary communication standard that was developed by Caterpillar Inc. The Cat Data Link requires a positive line and a negative line. The positive line is connected to terminal "J1-10" of the machine ECM. The negative line is connected to terminal "J1-20" of the machine ECM.
The electronic control system analyzes input signals and the electronic control system determines if an output signal should be sent to the EDCs on the propulsion pumps. The forward EDC on the left propulsion pump is controlled at terminal "J1-48" of the machine ECM. The reverse EDC on the left propulsion pump is controlled at terminal "J1-49" of the machine ECM. The forward EDC on the right propulsion pump is controlled at terminal "J1-51" of the machine ECM. The reverse EDC on the right propulsion pump is controlled at terminal "J1-52" of the machine ECM.
When the electronic control system determines that the propulsion lever is in the range of the REVERSE position the machine ECM generates an output signal from terminal "J1-12". This signal operates the backup alarm.
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| Illustration 5 | g01429399 |
The connector "J2" for machine ECM | |
When the main power relay is energized, power transfers from the circuit breaker for limp home mode to terminal "J2-1" of machine ECM (8). The machine ECM uses this voltage input in order to determine if the propulsion system should be actuated. When the engine is started and the propulsion lever is not in the neutral position, the electronic control system for the machine will not operate the propulsion system.
Machine ECM (8) receives a digital input signal from the speed sensor on the left propulsion motor at terminal "J2-26". The machine ECM receives a second input signal from this speed sensor at terminal "J2-27". When the sensor is functioning properly, these input signals will have the same frequency. However, the frequency signals have a phase offset. The machine ECM uses the frequency of the signals in order to determine the speed of the track. The machine ECM determines the direction of travel by checking to see which terminal receives the leading signal and checking which terminal receives the lagging signal.
Machine ECM (8) receives a digital input signal from the speed sensor on the right propulsion motor at terminal "J2-33". The machine ECM receives a second input signal from this speed sensor at terminal "J2-32". Similar to the signals from the speed sensor on the left track, the input signals from the right speed sensor should have the same frequency except for the phases of the signals should be offset. The machine ECM uses the frequency of the signals in order to determine the speed of the track. The machine ECM determines the direction of travel by checking which terminal receives the leading signal and which terminal receives the lagging signal.
Machine ECM (8) receives a pulse width modulated input signal from contact "C" of the left sensor for decelerator at terminal "J2-15". The machine ECM receives a pulse width modulated input signal from contact "C" of the right sensor for decelerator at terminal "J2-16". The machine's electronic control system uses these input signals in the speed control logic.
The lines for CAN provide high speed communication between machine ECM (8) and the engine ECM. The CAN requires a positive line and a negative line. The machine ECM contains two positive lines for CAN and two negative lines for CAN. The positive lines are connected to terminal "J2-56" and to terminal "J2-67" of the machine ECM. The negative lines are connected to terminal "J2-68" and to terminal "J2-70" of the machine ECM.
The machine's electronic control system monitors the position of the propulsion lever. When the system determines that the propulsion lever is in the REVERSE range, machine ECM (8) directs a digital output signal from terminal "J1-12". This signal is sent to the backup alarm.
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| Illustration 6 | g01429401 |
Top of Operator Station (11) Operator control unit (12) Connector "J1" (13) Connector "J2" | |
Operator control unit (11) is mounted to the door of the compartment at the top of the operator station. This control unit has two 70-pin connectors. Connector "J1" (12) is the connector which is farthest from the hinge of the compartment door. Connector "J2" (13) is the connector which is closest to the hinge of the compartment door.
Operator control unit (11) monitors input devices which are located in the operator's station. The operator control unit communicates with machine ECM (8) through the Cat Data Link and the lines FOR CAN.
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| Illustration 7 | g01429402 |
Connector "J1" for the Operator Control Unit | |
When the electrical disconnect switch is in the ON position, power transfers from the operator ECM circuit breaker to the following terminals of operator control unit (11) : terminal "J1-31", terminal "J1-39" and terminal "J1-47". This voltage input provides the power for the processor. When the engine start switch is in the ON position, power transfers from contact "1" of the switch to terminal "J1-1" of the control unit for operator. This voltage input provides the wake-up signal to the operator control unit. The operator control unit is grounded at the following terminals: terminal "J1-13", terminal "J1-23" and terminal "J1-57".
After operator control unit (11) has been activated, the control unit generates a 5 volt power output signal from terminal "J1-11". Power transfers from this terminal to the following locations:
- Contact "6" of the sensor on the propulsion lever
- Contact "A" of the speed dial for propulsion.
Terminal "J1-21" of operator control unit (11) provides a ground path for the sensor on the propulsion lever and for the speed dial for propulsion.
After operator control unit (11) has been activated, the control unit generates an 8 volt power output signal from terminal "J1-44". Power transfers from this terminal to contact "A" of the steering sensor.
Terminal "J1-45" of operator control unit (11) provides a ground path for the steering sensor.
Machine ECM (8) and operator control unit (11) are externally similar. Due to the internal differences between the machine ECM and the operator control units, both the machine ECM and the operator control unit will have different part numbers. In order to prevent incorrect software installation, the harness configuration at each control unit provides a series of switch input signals. These signals identify the unit's function. Operator control unit (11) is wired as the following:
- Terminal "J1-26" (open)
- Terminal "J1-27" (ground)
- Terminal "J1-28" (ground)
- Terminal "J1-32" (open)
Operator control unit (11) communicates with the other control units on the machine and with electronic service tools through the Cat Data Link. The Cat Data Link is a proprietary communication standard that was developed by Caterpillar Inc. The Cat Data Link requires a positive line and a negative line. The positive line is connected to terminal "J1-10" of the operator control unit. The negative line is connected to terminal "J1-20" of the operator control unit.
Operator control unit (11) analyzes input signals from the propulsion lever and from the speed dial for propulsion. The propulsion lever provides an input signal to terminal "J1-36" of the operator control unit. The propulsion speed dial provides an input signal to terminal "J1-37" of the operator control unit. These signals are transferred to the machine ECM through the lines for CAN and through the Cat Data Link. The signal for the Cat Data Link is a backup to the signal for CAN.
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| Illustration 8 | g01429403 |
Connector"J2" for the Operator Control Unit | |
Operator control unit (11) monitors input signals from the following components in the propulsion system:
- Terminal "J2-15" for the steering sensor
- Terminal "J2-30" and terminal "J2-31" for the parking brake switch
- Terminal "J2-33" for the emergency stop switch
- Terminal "J2-54" and terminal "J2-55" for the propulsion mode switch
Operator control unit (11) simultaneously monitors the condition of the circuit at terminal "J2-30" and the circuit at terminal "J2-31" in order to determine the position of the parking brake switch. When the circuit at terminal "J2-30" is grounded and the circuit at terminal "J2-31" is floating, the control unit determines that the parking brake switch is in the OFF position. When the circuit at terminal "J2-30" is floating and the circuit at terminal "J2-31" is grounded, the control unit determines that the parking brake switch is in the ON position.
Operator control unit (11) simultaneously monitors the condition of the circuit at terminal "J2-54" and the circuit at terminal "J2-55" in order to determine the position of the propulsion mode switch. When the circuit at terminal "J2-54" is grounded and the circuit at terminal "J2-55" is floating, the control unit determines that the switch for the left propulsion mode is in the TRAVEL position. When the circuit at terminal "J2-54" is floating and the circuit at terminal "J2-55" is grounded, the control unit determines that the switch for the propulsion mode is in the MANEUVER position. When the circuit at terminal "J2-54" is floating and the circuit at terminal "J2-55" is floating, the control unit determines that the switch for propulsion mode is in the PAVE position.
Operator control unit (11) monitors the circuit at terminal "J2-33" in order to determine the position of the emergency stop switch on the instrument panel. When the switch is in the NORMAL position, the circuit at terminal "J2-33" is grounded. When the switch is in the STOP position, the circuit at terminal "J2-33" is open.
Terminal "J2-22" of operator control unit (11) provides a common ground for the following digital input devices in the propulsion system:
- Parking brake switch
- Emergency stop switch
- Switch for propulsion mode.
When the machine electronic control system determines that the propulsion mode switch is in the TRAVEL position, operator control unit (11) generates a digital output signal from terminal "J2-5". This signal energizes the shift solenoid. The shift solenoid is de-energized when the switch for the propulsion mode is in the PAVE position or when the switch is in the MANEUVER position.
When the machine electronic control system determines that the parking brake switch is in the OFF position, operator control unit (11) generates a digital output signal from terminal "J2-6". This signal energizes the parking brake solenoid. The parking brake solenoid is de-energized while the parking brake switch is in the ON position. Also the parking brake is de-energized when the machine electronic control system has determined that other operating parameters have dictated that the parking brake should be engaged.
The CAN lines provide high speed communication between the machine control units and the engine ECM. The CAN requires a positive line and a negative line. The operator control unit contains two positive lines for CAN and two negative lines for CAN. The positive lines are connected to terminal "J2-56" and to terminal "J2-67" of the operator control unit. The negative lines are connected to terminal "J2-68" and to terminal "J2-70" of the operator control unit.
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| Illustration 9 | g01429404 |
Rear of Engine (14) Connector "J1" (15) Connector "J2" (16) Engine ECM | |
The door on the right side of the machine provides access to engine ECM (16). The engine ECM has two 64-pin connectors. Connector "J1" (14) transfers information between the machine harness and the engine ECM. Connector "J2" (15) monitors components which are located on the engine.
Engine ECM (16) transfers engine speed information to machine ECM (8). The machine ECM uses this information to control machine speed.
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| Illustration 10 | g01429405 |
Power for Engine ECM and Ground Terminals | |
Engine ECM (16) receives power at the following terminals: terminal "J1-7", terminal "J1-8", terminal "J1-15" and terminal "J1-16". The engine ECM is grounded at the following terminals: terminal "J1-1", terminal "J1-2", terminal "J1-3", terminal "J1-9" and terminal "J1-10".
When the engine start switch is in the ON position, power transfers from contact "1" of the switch to terminal "J1-40" of the engine ECM. This voltage input provides the wake-up signal to the engine ECM.
The lines for CAN are connected to terminal "J1-20" and terminal "J1-21" of engine ECM (16). The Cat Data Link is connected to terminal "J1-23" and terminal "J1-24" of the engine ECM. The engine ECM transfers engine speed information to the machine ECM through the CAN. The Cat Data Link provides a backup means of communication between the engine ECM and the machine ECM. The Cat Data Link also allows the engine ECM to communicate with the Caterpillar Electronic Technician (ET).
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| Illustration 11 | g01429406 |
Platform for Screed (17) "J2" connector (18) ECM for screed (19) "J1" connector | |
ECM for screed (18) is located below the walkway for the operator on the left side of the screed. This ECM has two 70-pin connectors. Connector "J1" (19) is the left connector. Connector "J2" (17) is the right connector.
Screed ECM (18) works in conjunction with the operator control unit and the machine ECM in order to control the propulsion system. The ECM for the screed receives input signals from components on the screed.
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| Illustration 12 | g01429407 |
ECM Connector "J1" for the Screed | |
When the electrical disconnect switch is in the ON position, power transfers from the ECM for the screed circuit breaker to terminal "J1-31," and to terminal "J1-39" of ECM for screed (18). This voltage input provides the power for the processor. When the main power relay is energized, power transfers from the screed circuit breaker to terminal "J1-1," and to terminal "J2-1" of the ECM for the screed. This voltage input provides the wake-up signal to the screed ECM. The ECM for the screed is grounded at terminal "J1-13".
ECM for screed (18) communicates with the other control units on the machine through the Cat Data Link. The Cat Data Link requires a positive line and a negative line. The positive line is connected to terminal "J1-10" of the ECM for the screed. The negative line is connected to terminal "J1-20" of the ECM for the screed.
ECM for screed (18) monitors the position of the left emergency stop switch on the operator station for the screed and the position of the right emergency stop switch on the operator station of the screed. When both emergency stop switches are in the NORMAL position, terminal "J1-42" is grounded and terminal "J1-43" is floating. When either switch is in the STOP position, terminal "J1-43" is grounded and terminal "J1-42" is floating.
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| Illustration 13 | g01429408 |
Rear of Machine (20) Resistor for CAN | |
The electronic control system is equipped with three resistors for the CAN. One resistor for CAN (20) is located at the rear of the machine under the operator's platform.
Note: When the screed is installed on the tractor, the resistor is removed and the connector is plugged. When the screed is removed from the tractor, the plug should be removed from the connector and the resistor is reinstalled.
Differences in materials along the CAN bus can cause pulses of date 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 loss of data.
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 the machine or near the machine. RFI creates noise in the lines for communication which can also distort the original data signals. Also, RFI creates noise in the lines that can cause the date to be lost.
In order to prevent the loss of data in the lines for communication, a termination resistor is required at each end of the CAN bus. The resistors for the CAN act as termination resistors. The resistors for the CAN absorb unwanted noise in the system for communication which can result in abnormal machine operation.
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| Illustration 14 | g01429410 |
Right Side of Machine (21) Resistor for CAN | |
The second resistor for CAN (21) is located in the pump compartment on the right side of the machine. The door on the right side of the machine provides access to this component.
Note: When the screed is installed on the tractor, the resistor is removed and the connector is plugged. When the screed is removed from the tractor the connector should be unplugged and the resistor should be reinstalled.
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| Illustration 15 | g01429411 |
Underneath Operator Station of the Main Screed (22) Resistor for CAN | |
The third resistor for CAN (22) is located on the screed under the operator station for the main screed.
Note: When the screed is installed on the tractor, the resistor is removed and the connector is plugged. When the screed is removed from the tractor, remove the plug from the connector and reinstall the resistor.