Electronic Control Module (ECM)
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| Illustration 1 | g06279698 |
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Machine ECM (1) Controller (2) J1 Connector (3) J2 Connector | |
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| Illustration 2 | g06279720 |
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Connectors of Machine ECM (2) J1 Connector (3) J2 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 one 70-pin connector. The inputs and outputs to the ECM can be viewed through the Cat® Electronic Technician (Cat ET) Service Tool. Some information can be viewed depending upon the monitor type that the machine is equipped with. Input and output information can also be viewed using the Operator Monitor.
The ECM also communicates with sensors and other control modules using the CAN Data Link. The data link is bidirectional, allowing the Machine ECM to both receive and send information with the engine.
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. Most issues are not due to the ECM, and only after a full troubleshooting process should the ECM be replaced.
The 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 |
| 13 | Return | Return of PWM J1-65 |
| 15 | Return | Return of 8V |
| 56 | Power | 8V Supply |
| 65 | Power | Electronic Pump Solenoid |
| (1) | Contacts that are not listed are not used. |
| Machine ECM Connector J2 Contact Descriptions(1) | ||
|---|---|---|
| No. | Type | Pin Description |
| 44 | Input | Main Hydraulic Pump Pressure Sensor |
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| Illustration 3 | g06356527 |
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 controller will recognize the following types of sensor signals:
Frequency - The sensor will produce an AC signal (sine wave or square wave) that varies in frequency (Hz) as the condition changes.
Pulse Width Modulated - The sensor produces a digital signal and varies the duty cycle as the condition changes. The frequency of the signal will remain constant.
Sometimes the operator is provided a manual switch that can be used to change a condition of the machine.
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| Illustration 4 | g02263513 |
Note: The values in Table 3are for bench testing only. Values may not represent parameters for machine systems specifications.
| Operating Pressure | |
| Supply Voltage | +7V ~ +14V |
| Output Signal | 500 ± 100 Hz (PWM) |
| Output Range | 5% ~ 95% |
The main pump pressure sensor is an input to the machine ECM. The main pump is on the main control valve. The main pump pressure sensor monitors the pressure of the main pump oil in the main control valve high-pressure passages.
The pressure sensor sends a pulse width modulated (PWM) input to the machine ECM. This pressure information is used for pump control and travel speed.
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.
Proportional Reducing Solenoids
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| Illustration 5 | g06191521 |
Note: The values in Table 4 are for bench testing only. Values may not represent parameters for machine systems specifications.
| Current | 1.5 A (max at 80° C ambient) |
| Rated Voltage | 12 VDC |
| Coil Resistance | 4.7 ± 0.2Ω (T = 20° C) |
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| Illustration 6 | g06237029 |
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A - Port pressure (kPa) vs Current (mA) | |
The P-Port is blocked and does not allow pressure to the A-port. Therefore, the machine ECM must apply current to the solenoid to send pressure to the A-port of the valve.
The data link is a controller network used to pass information back and forth. The data link is designed to carry communications between the various controllers and the monitor. The data link is not a visible component. The network consists of internal control circuits and a wiring harness. The data link is bidirectional. The controllers can receive information and send information. Two 120 Ohm terminating resistors must be installed in the wiring harness in order for each data link to function properly.
An example of how the data link works would be the fuel level information. The fuel level sensor is connected to the machine ECM. The ECM then sends the fuel level information over the data link to the monitor. The monitor uses this information to display the fuel level.