AP655D and BG655D Asphalt Pavers Propel System Caterpillar

Illustration 1	g01361990
Left Side of Machine (1) Engine control circuit breaker

Engine control circuit breaker (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.

Engine control circuit breaker (1) is a manual reset circuit breaker. This circuit breaker is rated at 20 amp. The engine control circuit breaker receives power from the main circuit breaker when the electrical disconnect switch is in the ON position. Power transfers from the engine control circuit breaker to the following terminals on the engine ECM: terminal "J1-7", terminal "J1-8", terminal "J1-15" and terminal "J1-16".

Illustration 2	g01361992
Compartment at Front of Operator Station (2) Operator ECM circuit breaker (3) Right hanECM circuit breaker (4) Machine ECM circuit breaker (5) Operator control circuit breaker (6) Limp home circuit breaker (7) Propulsion override resistor (right track) (8) Propulsion override resistor (left track)

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 propulsion control system:

• Operator ECM circuit breaker (2)

• ECM circuit breaker (3) (right hand)

• Machine ECM circuit breaker (4)

• Operator control circuit breaker (5)

• Limp home circuit breaker (6)

When the electrical disconnect switch is in the ON position, power from the main circuit breaker is available at the following circuit breakers: operator ECM circuit breaker (2), operator ECM circuit breaker (3) (right hand) and machine ECM circuit breaker (4). When the main power relay is energized, power from the main circuit breaker is available at operator control circuit breaker (5) and at limp home circuit breaker (6).

Operator ECM circuit breaker (2) 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 left operator control unit: terminal "J1-31", terminal "J1-39" and terminal "J1-47".

Operator ECM circuit breaker (3) (right hand) is a manual reset breaker. This circuit breaker is rated at 20 amp. Power transfers from this circuit breaker to the following terminals for the right operator control unit: terminal "J1-31", terminal "J1-39" and terminal "J1-47".

Machine ECM circuit breaker (4) is a manual reset breaker. This circuit breaker is rated at 20 amp. Power transfers from this circuit breaker to the following terminals for the machine ECM: terminal "J1-31", terminal "J1-39" and terminal "J1-47".

Operator control circuit breaker "CB12" (5) is manual reset breaker. This circuit breaker is rated at 15 amp. Power transfers from this circuit breaker to the indicator in the left parking brake switch and to the indicator in the right parking brake switch.

Limp home circuit breaker (6) is a manual reset breaker. This circuit breaker is rated at 15 amp. Power transfers from the limp home circuit breaker to the following locations:

• Contact "1" of propulsion override resistor (7) (right track)

• Contact "1" of propulsion override resistor (8) (left track)

• Contact "5" of the right propulsion override switch

• Contact "5" of the left propulsion override switch

• Terminal "J1-1" of the machine ECM

• Terminal "J2-1" of the machine ECM

Propulsion override resistor (7) that is for the right track and propulsion override resistor (8) that is for the left track limit the speed at which the machine will operate when the propulsion override switches are used.

Illustration 3	g01361999
Compartment at Front of Operator Station (9) Machine ECM (10) Connector "J2" (11) Connector "J1"

Machine ECM (9) is mounted to the door of the compartment at the front of the operator station. The compartment door provides access to this component.

Machine ECM (9) controls the propulsion system. This ECM has two 70-pin connectors. Connector "J1" (11) and connector "J2" (10) receive input signals from components around the machine which monitor current machine operating conditions. System software compares the gathered input to information which is stored in the memory of the ECM. 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 (9) is programmed with self-diagnostic logic. Service information can be accessed by using the operator display on the machine or service information can be accessed by using the electronic service tool (Caterpillar ET).

Illustration 4	g01362002
Machine ECM (Connector "J1")

When the electrical disconnect switch is in the ON position, power transfers from the machine ECM circuit breaker to the following terminals for the machine ECM: 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 limp home circuit breaker 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

Machine ECM (9) provides a ground path for the speed sensor on the left propulsion motor and the speed sensor on the right propulsion motor 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 and the two operator control units are externally the same. However, due to internal differences, the machine ECM has a different part number than the operator control units. 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 shown:

• Terminal "J1-26" (ground)

• Terminal "J1-27" (open)

• Terminal "J1-28" (open)

• Terminal "J1-32" (ground)

Machine ECM (9) 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. 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 determines if a 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.

Illustration 5	g01362007
Machine ECM (Connector "J2")

When the main power relay is energized, power transfers from the limp home circuit breaker to terminal "J2-1" of the machine ECM. The machine ECM uses this voltage input in order to determine if the propulsion system should be actuated. When the active propulsion lever is out of the NEUTRAL position when the engine is started, the machine electronic control system does not operate the propulsion system.

Machine ECM (9) 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 which terminal receives the leading signal and which terminal receives the lagging signal.

Machine ECM (9) 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". Similarly to the signals from the speed sensor on the left track, the input signals from the right speed sensor should have the same frequency, but 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.

The CAN lines provide high speed communication between machine ECM (9) and the engine ECM. The CAN requires a positive line and a negative line. The machine ECM contains two positive CAN lines and two negative CAN lines. 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 active propulsion lever. When the system determines that the active propulsion lever is in the REVERSE range, machine ECM (9) directs a digital output signal from terminal "J2-2". This signal is sent to the backup alarm.

Illustration 6	g01362011
Left Operator Control Unit Under the Operator Seat (12) Left operator control unit (13) Connector "J1" (14) Connector "J2"

Left operator control unit (12) is located under the left operator seat. This control unit has two 70-pin connectors. Connector "J1" (13) is the front connector and connector "J2" (14) is the rear connector. The right operator station also contains a control unit. The right operator control unit is located under the right operator seat. The left operator control unit and the right operator control unit are the same.

Left operator control unit (12) monitors input devices which are located in the left operator station. The right operator control unit monitors devices which are located in the right operator station. These control units communicate with machine ECM (9) through the Cat Data Link and the CAN lines.

Note: Left operator control unit (12) may also be referred to as the “master” operator control unit. The right operator control unit may also be referred to as the “auxiliary” operator control unit.

Illustration 7	g01362014
Left Operator Control Unit (Connector "J1")

When the electrical disconnect switch is in the ON position, power transfers from the left operator ECM circuit breaker to the following terminals for the left operator control unit (12): 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 left operator control unit. This voltage input provides the “wakeup” signal to the left operator control unit. The left operator control unit is grounded at the following terminals: terminal "J1-13", terminal "J1-23" and terminal "J1-57".

After left operator control unit (12) 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 left propulsion lever

• Contact "A" of the left propulsion speed dial

Terminal "J1-21" of left operator control unit (12) provides a ground path for the sensor on the left propulsion lever and for the left propulsion speed dial.

After left operator control unit (12) has been activated, the control unit generates an 8 volt power output signal from terminal "J1-44". Power transfers from this terminal to the following locations:

• Contact "A" of the decelerator sensor for the left decelerator pedal

• Contact "A" of the left steering sensor

Terminal "J1-45" of left operator control unit (12) provides a ground path for the decelerator sensor and for the left steering sensor.

Machine ECM (9) and the two operator control units are physically the same. 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. Left operator control unit (12) is wired as follows:

• Terminal "J1-26" (open)

• Terminal "J1-27" (ground)

• Terminal "J1-28" (ground)

• Terminal "J1-32" (open)

Left operator control unit (12) 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 developed by Caterpillar. The Cat Data Link requires a positive line and a negative line. The positive line is connected to terminal "J1-10" of the left operator control unit. The negative line is connected to terminal "J1-20" of the left operator control unit.

Left operator control unit (12) analyzes input signals from the left propulsion lever and from the left propulsion speed dial. The left propulsion lever provides an input signal to terminal "J1-36" of the left operator control unit. The left propulsion speed dial provides an input signal to terminal "J1-37" of the left operator control unit. These signals are transferred to the machine ECM through the CAN lines and through the Cat Data Link. The Cat Data Link signal is a backup to the CAN signal.

Illustration 8	g01362017
Left Operator Control Unit (Connector "J2")

Left operator control unit (12) monitors input signals from the following components in the propulsion system:

• Left steering sensor (terminal "J2-15")

• Left decelerator sensor (terminal "J2-16")

• Left parking brake switch (terminal "J2-30" and terminal "J2-31")

• Left propulsion mode switch (terminal "J2-54" and terminal "J2-55")

• Operator station select switch (terminal "J2-61" and terminal "J2-62")

Left operator control station (12) 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 left 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 left 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 left parking brake switch is in the ON position.

Left operator control station (12) 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 left 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 left propulsion mode switch 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 left propulsion mode switch 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 left propulsion mode switch is in the PAVE position.

Left operator control station (12) simultaneously monitors the condition of the circuit at terminal "J2-61" and the circuit at terminal "J2-62" in order to determine the position of the operator station select switch. When the circuit at terminal "J2-61" is grounded and the circuit at terminal "J2-62" is floating, the control unit determines that the operator station select switch is in the LEFT position. When the circuit at terminal "J2-61" is floating and the circuit at terminal "J2-62" is grounded, the control unit determines that the operator station select switch is in the RIGHT position.

Terminal "J2-22" of left operator control unit (12) provides a common ground for the following digital input devices in the propulsion system:

• Parking brake switch

• Operator station select switch

• Propulsion mode switch

Left operator control unit (12) controls the ground path for the left operator station indicator. When the machine electronic control system determines that the left operator station is active, the left operator control station connects terminal "J2-13" to ground. When the right operator station is active, terminal "J2-13" is open.

When the machine electronic control system determines that the active propulsion mode switch is in the TRAVEL position, left operator control unit (12) generates a digital output signal from terminal "J2-5". This signal energizes the shift solenoid. The shift solenoid is de-energized while the active propulsion mode switch is in the PAVE position and/or when the switch is in the MANEUVER position.

When the machine electronic control system determines that the active parking brake switch is in the OFF position, left operator control unit (12) 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 active parking brake switch is in the ON position. The parking brake solenoid is de-energized when the machine electronic control system determines that other operating parameters dictate 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 left operator control unit contains two positive CAN lines and two negative CAN lines. The positive lines are connected to terminal "J2-56" and to terminal "J2-67" of the left operator control unit. The negative lines are connected to terminal "J2-68" and to terminal "J2-70" of the left operator control unit.

Illustration 9	g01362123
Left Operator Control Unit (Connector "J1")

Note: The wiring of connector "J1" of the right operator control unit is similar to the wiring of connector "J1" of the left operator control unit. The main differences include the following: power source to the unit, configuration of the controller identification terminals and location of the input components.

When the electrical disconnect switch is in the ON position, power transfers from the operator ECM circuit breaker (right hand) to the following terminals for the right operator control unit: 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 right operator control unit. This voltage input provides the “wakeup” signal to the right operator control unit. The right operator control unit is grounded at the following terminals: terminal "J1-13", terminal "J1-23" and terminal "J1-57".

After the right operator control unit 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 right propulsion lever

• Contact "A" of the right propulsion speed dial

Terminal "J1-21" of the right operator control unit provides a ground path for the sensor on the right propulsion lever and for the right propulsion speed dial.

After the right operator control unit has been activated, the control unit generates an 8 volt power output signal from terminal "J1-44". Power transfers from this terminal to the following locations:

• Contact "A" of the decelerator sensor for the right decelerator pedal

• Contact "A" of the right steering sensor

Terminal "J1-45" of the right operator control unit provides a ground path for the decelerator sensor and for the right steering sensor.

Machine ECM (9) and the two operator control units are externally the same. However, due to internal differences the machine ECM has a different part number than the operator control units. 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 right operator control unit is wired as follows:

• Terminal "J1-26" (ground)

• Terminal "J1-27" (open)

• Terminal "J1-28" (ground)

• Terminal "J1-32" (open)

The right operator control unit 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. The Cat Data Link requires a positive line and a negative line. The positive line is connected to terminal "J1-10" of the right operator control unit. The negative line is connected to terminal "J1-20" of the right operator control unit.

The right operator control unit analyzes input signals from the right propulsion lever and from the right propulsion speed dial. The right propulsion lever provides an input signal to terminal "J1-36" of the right operator control unit. The right propulsion speed dial provides an input signal to terminal "J1-37" of the right operator control unit. These signals are transferred to the machine ECM through the Cat Data Link. The Cat Data Link is the primary line of communication and the CAN is the backup.

Illustration 10	g01362032
Left Operator Control Unit (Connector "J2")

The right operator control station monitors input signals from the following components in the propulsion system:

• Right steering sensor (terminal "J2-15")

• Right decelerator sensor (terminal "J2-16")

• Right parking brake switch (terminal "J2-30" and terminal "J2-31")

• Right propulsion mode switch (terminal "J2-54" and terminal "J2-55")

The right operator control station 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 right 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 right 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 right parking brake switch is in the ON position.

The right operator control station 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 right 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 right propulsion mode switch 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 right propulsion mode switch 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 right propulsion mode switch is in the PAVE position.

Terminal "J2-22" of left operator control unit (12) provides a common ground for the following digital input devices in the propulsion system:

• Parking brake switch

• Propulsion mode switch

The right operator control unit controls the ground path for the right operator station indicator. When the machine electronic control system determines that the right operator station is active, the right operator control station connects terminal "J2-13" to ground. When the left operator station is active, terminal "J2-13" is open.

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 right operator control unit contains two positive CAN lines and two negative CAN lines. The positive lines are connected to terminal "J2-56" and to terminal "J2-67" of the right operator control unit. The negative lines are connected to terminal "J2-68" and to terminal "J2-70" of the right operator control unit.

Illustration 11	g01362066
Rear of Engine (15) Connector "J1" (16) Connector "J2" (17) Engine ECM

The door on the right side of the machine provides access to engine ECM (17). The engine ECM has two 64 pin connectors. Connector "J1" (15) transfers information between the machine harness and the engine ECM. Connector "J2" (16) monitors components which are located on the engine.

Engine ECM (17) transfers engine speed information to machine ECM (9). The machine ECM uses this information to control machine speed.

Illustration 12	g01362107
Engine ECM Power and Ground Terminals

Engine ECM (17) 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 “wakeup” signal to the engine ECM.

The CAN lines are connected to terminal "J1-20" and terminal "J1-21" of engine ECM (17). 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 electronic service tool (Caterpillar ET).

Illustration 13	g01362112
Rear of Machine (18) CAN resistor

The electronic control system is equipped with two CAN resistors. One CAN resistor (18) is located at the rear of the machine under the operator platform.

Differences in materials along the CAN bus can cause data pulses in the bus to reflect back through the bus. This condition 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 or near the machine. RFI creates noise in the communication lines which can also distort the original data signals and cause data loss.

In order to prevent loss of data in the communication lines, a termination resistor is required at each end of the CAN bus. The CAN resistors act as termination resistors. The CAN resistors absorb unwanted noise in the communication system which can result in abnormal machine operation.

Illustration 14	g01362116
Right Side of Machine (19) CAN resistor

Second CAN resistor (19) 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.