Electronic Control Module (ECM)
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| Illustration 1 | g06114574 |
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Machine ECM (1) Controller (2) J1 Connector (3) J2 Connector | |
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| Illustration 2 | g06117000 |
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Pin identification (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 two 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 Controller Area Network (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.
| Machine ECM Connector J1 Contact Descriptions | ||
|---|---|---|
| No. | Function | Type |
| 1 | Ground | Ground |
| 2 | PRV 8–10 Return | PRV Return |
| 3 | PRV 4-7 Return | PRV Return |
| 4 | + Battery | Battery (+) |
| 5 | PRV 1-3 Return | PRV Return |
| 6 | Straight Travel Pressure Sensor | Analog Active Input |
| 8 | CAN 2 + : Machine Data Link | CAN 2 + |
| 9 | CAN 1 + : J1939 | CAN 1 + |
| 12 | Boom Up Control Pressure Sensor | Analog Active Input |
| 13 | Right Travel Pressure Sensor | Analog Active Input |
| 14 | Standard Implement Pilot Pressure Sensor/Left Travel Pressure Sensor | Analog Active Input |
| 15 | 5V Supply | 5V Supply 1 |
| 16 | Joystick Pilot Pressure Sensor/Implement Pressure Sensor | Analog Active Input |
| 17 | Boom Down Control Pressure Sensor | Analog Active Input |
| 22 | Hydraulic Lock Solenoid | PRV 1 |
| 23 | Swing Brake Solenoid | PRV 2 |
| 24 | Travel Speed Solenoid | PRV 3 |
| 27 | 2 - : Machine Data Link | CAN 2 - |
| 28 | CAN 1 - : J1939 | CAN 1 - |
| 33 | Swing Control Pressure Sensor | Analog Active Input |
| 34 | Analog & PWM Return 1 | Analog & PWM Return 1 |
| 41 | Key Switch | Key Switch |
| 42 | Boom Regeneration PRV | PRV 4 |
| 43 | Straight Travel Solenoid | PRV 5 |
| 61 | NFC 1 Solenoid | PRV 6 |
| 62 | NFC 2 Solenoid | PRV 7 |
| 81 | Power Shift Solenoid | PRV 10 |
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| Illustration 3 | g02655338 |
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Underside of Soft Switch Panel | |
| Switch Panel Connector J2 Contact Descriptions | ||
|---|---|---|
| No. | Function | Type |
| 1 | Machine CAN Data Link + | CAN + |
| 2 | Machine CAN Data Link - | CAN - |
| Switch Panel Connector J3 Contact Descriptions | ||
|---|---|---|
| No. | Function | Type |
| 1 | +B | +Battery |
| 2 | GND | Ground |
| 4 | Swing Priority Solenoid | On/Off |
| 7 | Heavy Lift Solenoid | On/Off |
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:
Analog - The sensor will produce a voltage signal that changes as the conditions that the sensor is sensing, changes.
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.
In some cases the operator is provided a manual switch that can be used to change a condition of the machine.
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| Illustration 4 | g06115468 |
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| Illustration 5 | g06115475 |
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Sensor output | |
The values in Table 4 are for bench testing only. Values may not represent parameters for machine systems specifications.
| Operating pressure | 5 MPa |
| Supply Voltage | +5 ± .25 V |
| Output signal | Analog |
| Output range | 0.5 to 4.5 V |
| Pin assignment | 1: Voltage
2: Ground 3: Signal |
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 voltage signal to the machine ECM. The machine ECM uses the pressure information to reduce engine speed and pump flow during a boom down function. Also, the boom down control pressure sensor is used as an input along with the boom head end pressure sensor to determine when boom regeneration can be performed.
whenever the pilot pressure exceeds
Pressure sensor for boom up control is equipped on machines with Smartboom system installed. Boom up control pressure sensor measures the pilot oil pressure during a boom UP function. The pressure sensor for boom up control sends a voltage signal to the machine ECM. The machine ECM uses the pressure information to determine the activation of the boom up electronic check valve solenoid and the boom down electronic check valve solenoid.
Whenever the pilot pressure exceeds
Pressure sensor for swing control measures the pilot oil pressure during a swing function. The pressure sensor sends a voltage signal 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 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.
The implement pressure sensor 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 sensor. The implement pressure sensor sends an electrical signal to the machine ECM. The sensor information is used to control engine speed and pump control. Also, an electrical signal from the machine ECM energizes the swing brake solenoid valve to release the swing parking brake.
Note: The implement pressure sensor does not detect a boom lower or a swing operation.
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| Illustration 6 | 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% |
The negative flow control (NFC) pressure sensors for the drive pump and idler pump are inputs to the machine ECM. The machine ECM uses this pressure information to determine the hydraulic demand requested by the operator. The machine ECM then sends a PWM driver to the negative flow control solenoids to control the pump flow rate.
The NFC pressure sensors are located on the top on the main control valve in the end plate.
For more information on the NFC pressure sensors, refer to Systems Operation, "Negative Flow Control System".
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| Illustration 7 | g02263513 |
Note: The values in Table 6 are for bench testing only. Values may not represent parameters for machine systems specifications.
| Operating Pressure | 50 MPa |
| Supply Voltage | +7V ~ +14V |
| Output Signal | 500 ± 100 Hz (PWM) |
| Output Range | 5% ~ 95% |
Boom cylinder head end pressure sensor measures the hydraulic pressure on the head end of the boom cylinder. The pressure sensors send a pulse width modulated signal (PWM) input to the machine ECM. The pressure information is used for boom regeneration control.
Boom cylinder rod end pressure sensor measures the hydraulic pressure on the rod end of the boom cylinder. The pressure sensors send a pulse width modulated signal (PWM) input to the machine ECM. The pressure information is used for Smartboom control.
The drive pump pressure sensor and idler pump pressure sensors are inputs to the machine ECM. The drive pump and idler pump pressure sensors are located on the main control valve. The drive pump pressure sensor monitors the pressure of the drive pump oil in the front half of the main control valve high-pressure passages. The idler pump pressure sensor monitors the idler pump oil pressure in the rear half of the main control valve high-pressure passages.
The pressure sensors send 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. The outputs of the ECMs are listed in tables 1,2, and 3.
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| Illustration 8 | 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 | 41.5 ± 2.1Ω (T=20° C) |
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.
Boom Up Electronic Check Solenoid Valve
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| Illustration 9 | g03678894 |
Note: The values in Table 9 are for bench testing only. Values may not represent parameters for machine systems specifications.
| Rated Voltage | 24 VDC |
| Coil Resistance | 22.4 ± 1.0 Ω (T=20° C) |
The boom up electronic check solenoid valve is an output of the Machine ECM. The boom up electronic check solenoid valve is energized in order to enable a boom Raise operation to occur. When the boom up electronic check solenoid valve is de-energized the boom cylinder head end oil is routed to both ends of the drift reduction valve, thus not allowing the boom to RAISE.
Boom Down Electronic Check Solenoid Valve
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| Illustration 10 | g03679000 |
Note: The values in Table 9 are for bench testing only. Values may not represent parameters for machine systems specifications.
| Rated Voltage | 24 VDC |
| Coil Resistance | 24.0Ω (T=20° C) |
The boom down electronic check solenoid valve is an output of the Machine ECM. The boom down electronic check solenoid valve is energized in order to enable the Smartboom system to drain directly into the makeup oil circuit. When the boom down electronic check solenoid valve is de-energized the boom cylinder rod end oil is not allowed to drain directly to the makeup oil circuit by a check valve within the boom down electronic check solenoid valve.
Proportional Reducing Solenoid Valve
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| Illustration 11 | g02703776 |
Note: The values in Table 10 are for bench testing only. Values may not represent parameters for machine systems specifications.
| Current Range | 0 mA ~ 700 mA |
| Coil Resistance | 15.0 ± 0.75Ω (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 12 | g02304374 |
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Valve cutaway, hydraulic schematic symbol, and electrical connector designation | |
Note: The values in Table 11 are for bench testing only. Values may not represent parameters for machine systems specifications.
| Current Range | 0 mA ~ 700 mA |
| Coil Resistance | 15.0 ± 0.75Ω (T=20° C) |
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| Illustration 13 | g02304414 |
Reverse PRV's have the P-port open to the A-port with no current applied. Therefore, the machine ECM applies current to the PRV in order to decrease the pressure at the A-port.
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.