CAP AS-BEARING 1540386 - Caterpillar

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Diagram of the machine control electronic communication system (1) Machine ECM (2) Implement ECM (3) Travel pedal (4) Engine ECM (5) CAN A data link (6) Machine monitor (7) Machine security system (8) CAN B data link (9) Operator control panel (10) Product link (11) Service connector (12) Communication adapter III (13) Electronic technician (ET)The following will cover information that pertains primarily with the bucket system and components that are controlled by the machine ECM and the attachment implement ECM.When using this manual for the troubleshooting of the electrical system circuits, the complete electrical system schematic for your machine should also be used. Quick reference electrical connection diagrams are included throughout this manual. However, these diagrams do not show the machine wiring harness connections that are part of the circuit. The complete electrical system schematic illustrate all machine wiring harness connectors and the locations on the machine.Electronic Control Module (ECM)
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Electronic control modules are located to left rear side of the machine (1) Machine ECM (2) Implement ECMMachine ECM
The machine ECM is the control module that will use the programmed control logic to manage the operation of most of the machine functions. The machine ECM will use the data from the various input devices to determine the appropriate output response to operator commands.The machine ECM determines all of the appropriate output commands and communicates this information to the Implement ECM on the SAE J1939 (CAN) data link.The machine ECM will activate outputs in order to energize or de-energize solenoids that will control the installed machine functions.Except for the operation of the engine, the machine ECM will control the major machine functions on the machine. The machine ECM controls the following functions:
Electronic shifting of the transmission and travel functions
Implement control
Left and the right electronic joystick operation
Oscillating axle operationIn addition, the machine ECM will control the following attachment functions when installed on the machine:
Auxiliary hydraulics
Medium pressure hydraulics
Overload warning
Quick coupler
Travel alarm
Travel lock
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Machine ECM connectors (1) J1 connector (2) J2 connectorPin Locations for Machine ECM
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Machine ECM connector (70-pin)
Table 1
Machine ECM - J1 Contact Connections    
Pin Location    Function    Description    
44     8 VDC sensor supply     Voltage input    
45     8 VDC sensor return     Return (ECM ground)    
Table 2
Machine ECM - J2 Contact Connections    
Pin Location    Function    Description    
25     Bucket pilot pressure "A" sensor     Analog input    
26     Bucket pilot pressure "B" sensor     Analog input    Inputs
The inputs describe the status of the machine systems. Two types of inputs exist. The inputs can be either a switch type or a sensor type. Switches provide an open, a ground, or a + battery signal to the inputs of the controller. Sensors (frequency, PWM, or voltage) provide a changing signal to the sensor inputs of the controller.Sensor Inputs
Most sensor input circuits have an internal ECM "pull up voltage" that is present at the ECM contacts. An above normal voltage is internally connected to the ECM input circuit