Electronic Control Module (ECM)
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| Illustration 1 | g06411309 |
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(1) J1 Connector
(2) J2 Connector | |
The ECM bases decisions on input information and memory information. After the ECM receives the input and outputs of the ECM are connected to the machine harness by two 70-pin connectors (1) and (2). The inputs and outputs to the ECM can be viewed through the Caterpillar Electronic Technician (Cat ET).
Note: Only the complete ECM is serviceable (no lower-level 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 in order 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 2 J1 Contact Descriptions | ||
| No. | Type | Function |
| 11 | Sourcing Driver Supply | Air Compressor Oil Pressure |
| 22 | Sourcing Driver Output | Air Compressor Outlet Air Temp Supply |
| 29 | Sourcing Driver Output | Air Compressor Interstage Air Temp |
| 49 | PWM Driver 2 | Air Compressor Inlet Close Solenoid |
| 50 | PWM Driver Return | Air Compressor Inlet Close Solenoid / Air Compressor Inlet Open Solenoid / Air Compressor Spiral Valve |
| 51 | PWM Driver 3 | Air Compressor Inlet Open Solenoid |
| 52 | PWM Driver 4 | Air Compressor Spiral Valve |
| 56 | Sourcing Driver Return | Air Compressor Oil Pressure |
| Machine ECM 2 J2 Contact Descriptions | ||
| No. | Type | Function |
| 22 | Sourcing Driver Return | Air Compressor Outlet Air Temp / Air Compressor Interstage Air Temp |
| 60 | Sourcing Driver Signal | Air Compressor Oil Pressure |
| Machine ECM 3 J1 Contact Descriptions | ||
| 11 | 5V Supply | Air Compressor Dry Side Pressure / Air Supply Wet Side Pressure |
| 21 | 5V Return | Air Compressor Dry Side Pressure / Air Supply Wet Side Pressure |
| Machine ECM 3 J2 Contact Descriptions | ||
| 59 | Sourcing Driver Signal | Air Compressor Dry Side Pressure |
| 60 | Sourcing Driver Signal | Air Compressor Wet Side Pressure |
Low-Pressure Compressor (If Equipped)
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| Illustration 2 | g06284311 |
| (1) Intake air pressure sensor | |
The Air Compressor Intake Air Pressure Sensor (1) is installed in the air Induction tube assembly to measure the vacuum created by suction. As the filters become clogged, the air restriction increases. When the vacuum reaches the set point of the Air Compressor Intake Air Pressure Sensor, the ECM will activate the warning for AIR FILTER RESTRICTION.
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| Illustration 3 | g06284319 |
| (2) Discharge Temperature Sensor | |
The Compressor Discharge Temperature Sensor (2) is on the compressor discharge and monitors the temperature of the air/oil mixture leaving the compressor. The Compressor Discharge Temperature Sensor is connected to the AUX Machine ECM 2 and will trigger an alarm at
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| Illustration 4 | g06351937 |
| (3) Dry Side Pressure Sensor | |
The Dry Side Pressure Sensor (3) is located near the low-pressure air receiver tank. The Dry Side Pressure Sensor is connected to the Auxiliary Machine ECM 3 and is used to prevent over-pressurization of the air receiver tank.
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| Illustration 5 | g06351941 |
| (4) Wet Side Pressure Sensor | |
The Wet Side Pressure Sensor (4) is located near the low-pressure air receiver tank. The Wet Side Pressure Sensor is connected to the Auxiliary Machine ECM 3 and is used to prevent over-pressurization of the air receiver tank.
The wet side pressure sensor, along with the dry side pressure sensor, are also used to measure a pressure differential. From that differential pressure, the operator can be alerted to the filter / separator is clogged or damaged.
Compressor Oil Pressure Sensor
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| Illustration 6 | g06351962 |
| (5) Compressor Oil Pressure Sensor | |
The Compressor Oil Pressure Sensor (5) is located inside the control box and monitors the Compressor Oil Pressure. If the oil pressure in the system gets too low, the air system will not be allowed to turn on.
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| Illustration 7 | g06364416 |
| (6) Bit Air Pressure Sensor | |
The Bit Air Pressure Sensor (6) is located after the air on / off valve by the engine on the right side of the drill. The Bit Air Pressure Sensor is connected to the Auxiliary ECM 3 and is monitored in the cab on the monitoring system. In the event of the Bit becoming jammed, bit pressure will rise and notify the operator on the cab monitoring system.
High-Pressure Compressor (if Equipped)
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| Illustration 8 | g06284311 |
| (1) Intake air pressure sensor | |
The Air Compressor Intake Air Pressure Sensor (1) is installed in the air Induction tube assembly to measure the vacuum created by suction. As the filters become clogged, the air restriction increases. When the vacuum reaches the set point of the Air Compressor Intake Air Pressure Sensor, the ECM will activate the warning for AIR FILTER RESTRICTION.
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| Illustration 9 | g06364425 |
| (11) Discharge Temperature Sensor | |
The Compressor Discharge Temperature Sensor (11) is on the compressor discharge and monitors the temperature of the air/oil mixture leaving the compressor. The Compressor Discharge Temperature Sensor is connected to the AUX Machine ECM 2 and will trigger an alarm at
Compressor Oil Pressure Sensor
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| Illustration 10 | g06352220 |
| (12) Compressor Oil Pressure Sensor | |
The Compressor Oil Pressure Sensor (12) is located inside the control box and monitors the Compressor Oil Pressure.
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| Illustration 11 | g06352222 |
| (13) Dry Side Pressure Sensor | |
The Dry Side Pressure Sensor (13) is located near the low-pressure air receiver tank. The Dry Side Pressure Sensor is connected to the Auxiliary Machine ECM 3 and is used to prevent over-pressurization of the air receiver tank.
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| Illustration 12 | g06352223 |
| (14) Wet Side Pressure Sensor | |
The Wet Side Pressure Sensor (14) is located near the low-pressure air receiver tank. The Wet Side Pressure Sensor is connected to the Auxiliary Machine ECM 3 and is used to prevent over-pressurization of the air receiver tank.
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| Illustration 13 | g06364416 |
| (6) Bit Air Pressure Sensor | |
The Bit Air Pressure Sensor (6) is located after the air on / off valve by the engine on the right side of the drill. The Bit Air Pressure Sensor is connected to the Auxiliary ECM 3 and is monitored in the cab on the monitoring system. In the event of the Bit becoming jammed, bit pressure will rise and notify the operator on the cab monitoring system.
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| Illustration 14 | g06364429 |
| (19) Interstage Pressure Sensor | |
The interstage pressure sensor (19) is located on the discharge pipe between the low side and the high side of the air compressor. The interstage pressure sensor is connected to the AUX machine ECM 2 and will trigger and alarm at
Low-Pressure Compressor (If Equipped)
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| Illustration 15 | g06351984 |
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(7) Control Box
(8) Compressor Inlet Close N/O Solenoid Valve (9) Compressor Inlet Open N/C Solenoid Valve (10) Spiral Valve Solenoid | |
The Compressor Inlet Close N/O (Normally Open) Valve (8) allows air pressure through to Port 1 holding the Poppet Intake Valve closed, and to the Running Blowdown to dump air from the Air Receiver Tank, so the Compressor is unloaded.
When the solenoid on the Compressor Inlet Close N/O Valve is de-energized, the Compressor Inlet Close N/O Valve supplies signal air to Port 1A on the Poppet Intake Valve to close the Poppet Plate and sends pilot signals to the Running Blowdown Valve that causes the valve to open and exhaust air through the Muffler. When the solenoid on the Compressor Inlet Close N/O Valve is energized, the valve closes and the signal air to Port 1A and pilot signal to the Running Blowdown Valve is lost through the loop line and Orifice to Port 3. The loss of pilot air to the Running Blowdown Valve causes the valve to close which opens the Poppet Plate and loads the Compressor in maximum displacement mode.
The Compressor Inlet Open N/C (Normally Closed) Valve (9) only goes to Port 2, to open the Poppet Intake Valve, so when de-energized the Compressor is unloaded.
When the solenoid on the Compressor Inlet Valve is energized, the N/C Solenoid Valve opens and sends signal air to Port 2 that opens the Poppet Plate. The running Blowdown Valve closes so the Compressor loads into maximum displacement mode. Both the Compressor Inlet Close N/O and the Compressor Inlet Open N/C Valves are designed to be in "fail-safe" mode so that if the power supply or solenoid fails, the Compressor will not load.
The Spiral Valve Solenoid (10) controls the spiral valve regulator which is used to reduce compressor volume by rotating the spiral valve.
The instrument group consists of an air pressure gauge and compressor discharge temperature gauge. The air pressure gauge continually monitors the sump pressure at various loads and/or unload conditions. The compressor discharge temperature gauge monitors the temperature of the air/fluid moisture leaving the compressor unit .
Protective shutdown switches are provided to actuate the power source shutdown system in the event of a malfunction. The compressor discharge temperature switch is a normally closed switch which will open if the discharge temperature exceeds normal operating range. Also provided is a temperature transducer which monitors the discharge temperature via the control screen.
The pressure gauge continually monitors the pressure inside the receiver sump at various load and unloaded conditions.
High-Pressure Compressor (If Equipped)
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| Illustration 16 | g06352230 |
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(16) N/O Solenoid Valve
(17) N/C Solenoid Valve (18) Spiral Valve Solenoid | |
When de-energized (open) air flows through the N/O Solenoid Valve to Port 1 of the Poppet Intake Valve, holding the valve closed, and to pilot the Running Blowdown Valve open, to dump air. This ensures that the Compressor is unloaded when the N/O Solenoid is de-energized.
When the N/O Solenoid Valve is energized, the N/O Solenoid Valve closes and blocks air flow to Port 1 of the Poppet Intake Valve. The pressure signal to Port 1 vents through the loop line to Port 3. The pressure signal to the Pilot Port of the Running Blowdown Valve is also vented, so the Running Blowdown Valve closes, allowing pressure to build in the Air Receiver Tank.
The N/C Solenoid Valve is supplied air flow from the Pressure Reducing Regulator.
When energized the N/C Solenoid Valve opens and air flows though to Port 2 of the Poppet Intake Valve. This opens the Poppet Intake Valve, allowing maximum air to be drawn into the Compressor.
On startup, if the compressor oil is cold (less than
If compressor oil temperature is above
If the compressor oil is already above
The Spiral Valve Solenoid (10) controls the spiral valve regulator which is used to reduce compressor volume by rotating the spiral valve.
The instrument group consists of an air pressure gauge and compressor discharge temperature gauge. The air pressure gauge continually monitors the sump pressure at various loads and/or unload conditions. The compressor discharge temperature gauge monitors the temperature of the air/fluid moisture leaving the compressor unit .
Protective shutdown switches are provided to actuate the power source shutdown system in the event of a malfunction. The compressor discharge temperature switch is a normally closed switch which will open if the discharge temperature exceeds normal operating range. Also provided is a temperature transducer which monitors the discharge temperature via the control screen.
The pressure gauge continually monitors the pressure inside the receiver sump at various load and unloaded conditions.
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 (Cat ET). 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 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 output information to the Caterpillar ET.
Note: An electronic control module that uses the Cat Data Link will have a module identifier. The MID for the Machine Electronic Control Module is 039.
A data link is required for communication with the service tool (Cat ET) and the electronic control modules as well as instrument clusters and other devices that use this communication protocol. The data link is not used in order to broadcast any diagnostic information.