Electronic Control Module (ECM)
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| Illustration 1 | g02612416 |
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Machine ECM (1) Controller (2) J1 Connector (3) J2 Connector | |
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| Illustration 2 | g02613001 |
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Connectors for Machine ECM (2) Connector (3) Connector | |
The output from the Machine ECM is based on input information from the sensors. The output commands are based on the software programmed into the control module. After the Machine ECM receives the input information, the ECM sends a corresponding response to the outputs. The inputs and outputs of the ECM are connected to the machine harness by two 54-pin connectors (J1 and J2). The inputs and outputs to the ECM can be viewed through the Caterpillar Electronic Technician (Cat ET). Input and output information can also be viewed using the Operator Monitor.
The ECM also communicates with sensors and other control modules via the CAN Data Link. The data link is bi-directional, allowing the Machine ECM to both receive and send information with the Engine ECM. The Machine ECM also communicates to input and output components that are directly connected to the Switch Panel. The Switch Panel is used to link input and output components to the Machine ECM via the CAN Data Link.
Note: Only the complete ECM is serviced (no lower levels components). The ECM must be replaced if the ECM is damaged. Replace the ECM if a failure is diagnosed.
The Cat Data Link is used to provide a connection for the service tool for troubleshooting, testing, and calibrations. The data link is bidirectional. The data link allows the ECM to receive information. The data link also allows the ECM to send information.
| Machine ECM Connector J1 Contact Descriptions(1) | ||
|---|---|---|
| No. | Type | Pin Description |
| 1 | Power | +Battery |
| 2 | Ground | Ground |
| 3 | Output | Swing Brake Solenoid |
| 17 | Input | Boom Down Control Pressure Sensor |
| 23 | Input | Key Switch |
| 25 | Output | Travel Speed Change Solenoid |
| 27 | Power | Power Supply for Sensor (8V) |
| 29 | Input | Left Travel Pressure Switch |
| 30 | Input | Right Travel Pressure Switch |
| 31 | Input | Implement Pressure Switch |
| 35 | Input | Swing Control Pressure Sensor |
| 39 | Input | Straight Travel Pressure Switch |
| 43 | Output | Straight Travel Solenoid |
| (1) | Contacts that are not listed are not used. |
| Machine ECM Connector J2 Contact Descriptions | ||
|---|---|---|
| No. | Type | Pin Description |
| 8 | Output | Power Shift Pressure EPRV |
| 9 | Output | Boom Regeneration REPRV |
| 19 | Ground | PRV Return |
| 21 | Ground | PRV Return |
| 27 | Output | Hydraulic Lock Cancel Switch |
| 28 | Output | Swing Priority Solenoid |
| 43 | Output | Negative Flow Control 2 Limit EPRV |
| 47 | Input/Output | CAN (J1939) Data Link + |
| 48 | Input/Output | CAN (J1939) Data Link - |
| 50 | Input/Output | Machine CAN Data Link + |
| 51 | Input/Output | Machine CAN Data Link - |
| 53 | Output | Negative Flow Control 1 Limit EPRV |
| Switch Panel ECM Connector J2 Contact Descriptions | ||
|---|---|---|
| No. | Type | Pin Description |
| 1 | Input/Output | Machine CAN Data Link + |
| 2 | Input/Output | Machine CAN Data Link - |
| Switch Panel ECM Connector J3 Contact Descriptions | ||
|---|---|---|
| No. | Type | Pin Description |
| 1 | Power | +Battery |
| 2 | Ground | Ground |
| 7 | Output | Heavy Lift Solenoid |
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. The inputs to ECMs are listed in tables 2,3, and 4.
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| Illustration 3 | g02263393 |
Note: The values in Table 5 are for bench testing only. Values may not represent parameters for machine systems specifications.
| Operating pressure | 10 MPa |
| Supply Voltage | +7V ~ +14V |
| Output signal | 500 ± 100 Hz (PWM) |
| Output range | 5% ~ 95% |
Boom Down Control Pressure Sensor
Pressure sensor for boom down control measures the pilot oil pressure during a boom DOWN function. The pressure sensor for boom down control sends a pulse width modulated signal (PWM) input to the machine ECM. The machine ECM uses the pressure information to reduce engine speed and pump flow during a boom down function. Also, whenever the pilot pressure exceeds
Pressure sensor for swing control measures the pilot oil pressure during a swing function. The pressure sensor sends a pulse width modulated signal (PWM) input to the machine ECM. The machine ECM uses the pressure information to control the swing priority solenoid valve. Whenever the pilot pressure exceeds
Pressure sensor for swing control is also used to prevent oil loss over the crossover relief valve at the start of a swing function. The swing operation is detected with the swing pilot pressure sensor. The swing load pressure is detected with the idler pump pressure sensor. The main pump flow is reduced when the idler pump pressure sensor is higher than the crossover relief valve pressure setting determined by the machine ECM. The machine ECM sends a PWM signal in order to destroke the idler pump.
The machine ECM also reduces the idler pump flow during inching operation. Swing inching is detected by the pressure sensor for swing control. This function is only activated when no other implements are being operated.
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| Illustration 4 | g02332474 |
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Pressure switch | |
Note: The values in Table 6 are for bench testing only. Values may not represent parameters for machine systems specifications.
| Actuation Pressure | 490 ± 49 kPa |
| Deactuation Pressure | 294 kPa minimum |
| Rating | + 12V to + 32 V DC
0.01 Amp to 1 Amp |
| Pressure Range | 0 to 10 MPa |
Left Travel Pressure Switch and Right Travel Pressure Switch
The left travel pressure switch and right travel pressure switch detects a travel operation. The travel pressure switches send an input signal to the machine ECM. The machine ECM uses the switch information to control the engine speed and pump control.
The implement pressure switch sends an input signal to the machine ECM. When the joysticks are moved from the NEUTRAL position for a boom UP, stick IN, stick OUT, bucket IN, or a bucket OUT operation, pilot oil is directed to the implement pressure switch. The increase of pilot pressure activates the implement pressure switch. The implement pressure switch sends an electrical signal to the machine ECM. The switch information is used to control engine speed and pump control. Also, an electrical signal from the machine ECM energizes the swing brake solenoid valve in order to release the swing parking brake.
Note: The implement pressure switch does not detect a boom lower or a swing operation.
The ECM responds to inputs by sending electrical signals to the outputs. The outputs can create an action or the outputs can provide information to the operator or service technician. The outputs of the ECMs are listed in tables 2,3, and 4.
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| Illustration 5 | g01158530 |
Note: The values in Table 7 are for bench testing only. Values may not represent parameters for machine systems specifications.
| Rated Voltage | 24 VDC |
| Coil Resistance | 32.0 ± 3.2Ω (T=20° C) |
The swing brake solenoid is an output of the Machine ECM. The swing brake solenoid is energized in order to release the swing brake. When the swing brake is released, the upper structure is free to rotate. The swing brake is released when the control levers are actuated. The swing brake solenoid is de-energized approximately 6.5 seconds after any lever is moved to NEUTRAL position.
The travel speed solenoid is an output of the Machine ECM. When the travel speed solenoid is active, the machine can travel at high speed. The travel speed solenoid is active when the travel speed mode switch is set to "RABBIT (high)" mode. The travel speed also depends on the delivery pressure of the main pump. If the delivery pressure of the main pump is high, the travel speed solenoid is de-energized. When the delivery pressure of the main pump is low, the travel speed solenoid is energized.
The straight travel solenoid is energized to maintain straight travel even though a swing operation or implement operation is performed during travel.
The hydraulic lock solenoid is an output of the Machine ECM. The hydraulic lock solenoid is energized in order to enable the primary hydraulic pressure. The hydraulic lock solenoid is de-energized in order to disable the primary hydraulic pressure.
This solenoid is activated while the key switch is in the ON position and the hydraulic lock lever is in the UNLOCK position.
When swing priority is activated, the output flow from the idler pump supplies hydraulic oil to the swing hydraulic circuit. Since swing priority increases the swing acceleration, swing priority is useful for loading operations. Swing priority is also useful for leveling operations and trenching operations when higher swing force is required.
Proportional Reducing Solenoid Valve
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| Illustration 6 | g02703776 |
Note: The values in Table 8 are for bench testing only. Values may not represent parameters for machine systems specifications.
| Current Range | 0 mA ~ 700 mA |
| Coil Resistance | 11.5 ± 0.5Ω (T=20° C) |
The power shift pressure PRV is used to destroke the main pump under load to maintain engine speed. The main functions of the PRV, in conjunction with, the monitoring system, are listed below:
- The PRV manages the transfer to engine power into hydraulic power as needed.
- The system control the output of the pump according to the workload, improving fuel efficiency.
Negative Flow Control 1 Limit PRV and Negative Flow Control 2 Limit PRV
Two proportional reducing valves for negative flow control are used to control the amount of NFC signal to the pump regulators. The machine ECM receives various input signals to control the flow limitation from the main hydraulic pumps. When the NFC valves are energized by the machine ECM, pilot oil pressure is directed to the main hydraulic pump regulators from the pilot manifold. The pilot oil pressure causes the hydraulic pumps to destroke which reduces hydraulic oil flow.
Reverse Proportional Reducing Solenoid Valve
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| Illustration 7 | g02304374 |
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Valve cutaway, hydraulic schematic symbol, and electrical connector designation | |
Note: The values in Table 9 are for bench testing only. Values may not represent parameters for machine systems specifications.
| Current Range | 0 mA ~ 700 mA |
| Coil Resistance | 11.5 ± 0.5Ω (T=20° C) |
The boom regeneration PRV is used in order to control the amount of regeneration oil in the boom circuit. The machine ECM receives an input signal from pressure sensor for boom down control and boom cylinder head end pressure sensor.
When the boom cylinder head end pressure is high and the pressure sensor for boom down control detects pilot pressure, the boom regeneration PRV remains de-activated. Pilot oil is then directed through the boom regeneration PRV and to the boom regeneration valve allowing regeneration.
When the boom cylinder head end pressure is low and the pressure sensor for boom down control detects pilot pressure, the boom regeneration PRV begins to receive a PMW signal from the machine ECM. The machine ECM begins to increase current flow which decreases the amount of pilot oil supplied to the boom regeneration valve. The boom regeneration circuit is then disabled.
The Cat Data Link is an input/output of the ECM. The data link uses the connector for the service port in order to communicate with the Caterpillar Electronic Technician. A data link connection is provided for the product link.
Note: The control for the product link provides a global positioning system for the machine.
The data link is bidirectional. The bidirectional link allows the ECM to input information and output information. The data link consists of the following parts: internal ECM circuits, the related harness wiring, the service tool connector and the connector for the product link. The Cat Data Link connects to the ECM at contact J2-16 (wire 892-BR(Brown)) and contact J2-25 (wire 893-GN(Green)).
- The ECM receives commands from the Cat ET in order to change the operating modes. The Cat ET will read the service codes that are stored in the memory of the ECM. The Cat ET will clear the service codes that are stored in the memory of the ECM.
- The ECM sends the input and the output information to the Caterpillar ET.
A Controller Area Network (CAN) Data Link allows communication between the Machine ECM, Engine ECM, and the input and output devices of the switch panel. The CAN Data Link allows for bi-directional electronic signals to be passed among the controllers and the switch panel. The data link allows the Machine ECM to be connected to sensors and actuators connected to the switch panel. The Machine ECM can also use the data link to communicate engine speed and/or torque requirements to the Engine ECM.