Electronic Control Modules ECMs
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| Illustration 1 | g06131427 |
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(1) Connector view from ECM side
(2) Connector view from harness side | |
The ECM bases decisions on input information and memory information. After the 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 70 contact connectors (J1 and J2). The inputs and outputs to the ECM can be viewed through the Caterpillar Electronic Technician (Cat ET).
In most instances when a diagnostic code or an event code is activated, the ECM is the least likely cause of the problem. When an ECM is suspected to have failed, always ensure that the latest software is flashed on the ECM. Verify that the ECM connections are secure. Then, verify that the problem is still active before replacing an ECM
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.
| Implement ECM Connector J1 Contact Descriptions(1) | ||
|---|---|---|
| No. | Type | Function |
| 44 | Sensor Power Output | 8 V Sensor Power |
| 45 | Sensor Power Return | 8 V Sensor Return |
| 54 | Sourcing Driver Return | Remote Steer Solenoid Return |
| 55 | Sourcing Driver Return | Steer Pilot Supply Solenoid Return |
| 66 | Sourcing Driver Output | Steer Pilot Oil Supply Solenoid |
| (1) | System-specific pin locations |
| Implement ECM Connector J2 Contact Descriptions | ||
|---|---|---|
| No. | Type | Function |
| 34 | PWM Input | Pilot Steer Manifold Pressure Sensor |
| 35 | PWM Input | Primary Steer Pressure Sensor |
| 38 | Switch to Ground Input | Secondary Steer Flow Switch |
| 40 | PWM Input | Articulation Angle Sensor |
| 41 | PWM Input | Articulation Angle Sensor |
| Machine ECM Connector J1 Contact Descriptions (1) | ||
|---|---|---|
| No. | Type | Function |
| 51 | Sourcing Driver Output | Reversing Steering Solenoid |
| (1) | Contacts that are not listed are not used. |
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 1 through 3 .
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| Illustration 2 | g06235947 |
The pilot steering pressure sensor is an input of the Implement ECM. The sensor connects to connector contact J2-34 of the Implement ECM. The sensor sends a PWM signal to the Implement ECM indicating system pressure.
The sensor has connector three contacts. The sensor receives +8 V sensor supply through contact 1 from connector contact J1-44. the sensor sends a signal to the Implement ECM through contact 3 at connector contact J1-34. Contact 2 is connected to the sensor reurn through connector contact J1-45.The duty cycle of the signal will vary in proportion to the system pressure. These PWM signals are inputs to the Implement ECM.
The Implement ECM records diagnostic codes that are associated with the pressure sensor (hydraulic pilot oil) as a CID 434. A record of the diagnostic code is made during machine operation.
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| Illustration 3 | g06265767 |
The primary steering pressure sensor is an input of the Implement ECM. The sensor connects to connector contact J2-35 of the Implement ECM. The sensor sends a PWM signal to the Implement ECM indicating system pressure.
The sensor has connector three contacts. The sensor receives +8 V sensor supply through contact 1 from connector contact J1-44. the sensor sends a signal to the Implement ECM through contact 3 at connector contact J2-35. Contact 2 is connected to the sensor reurn through connector contact J1-45.The duty cycle of the signal will vary in proportion to the system pressure. These PWM signals are inputs to the Implement ECM.
The Implement ECM records diagnostic codes that are associated with the pressure sensor (primary steering) as a CID 2470. A record of the diagnostic code is made during machine operation.
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| Illustration 4 | g06235952 |
The secondary steering flow switch is an input of the Implement ECM.
The switch connects to contact J2-38 of the Implement ECM.
When the engine speed is greater than 1700 rpm and speed is greater than
The Implement and Machine ECMs respond to decisions by sending electrical signals to the outputs. The outputs can create an action or the outputs can provide information to the operator or the service technician. The outputs of the Implement and Machine ECMs are listed in Tables 1,2, and 3.
- Reversible Steering Solenoid (if equipped)
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| Illustration 5 | g03566528 |
The reversible steering solenoid valve is an output of the Machine ECM. The Machine ECM energizes the reversible steering solenoid with approximately +24 DCV. Pressure oil will pass through the reversible steering solenoid valve when the reversible steering solenoid is energized. The reversible steering solenoid valve sends oil pressure to the steering neutralizers.
The reversible steering solenoid has a connector with two contacts. Connector contact 1 of reversible steering solenoid receives power from connector contact J1-51 of the Machine ECM. Connector contact 2 of the reversible steering solenoid is connected to ground.
- Steering Pilot Supply Solenoid
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| Illustration 6 | g03566530 |
The steering pilot supply solenoid valve is an output of the Implement ECM. The Implement ECM energizes the steering pilot supply solenoid with approximately +24 DCV. Pressure oil will flow through the steering pilot supply solenoid valve when the steering pilot supply solenoid is energized. The steering pilot supply solenoid valve sends oil pressure to the STIC steering pilot valve.
The steering pilot supply solenoid has a connector with two contacts. Connector contact 1 of steering pilot supply solenoid receives power from connector contact J1-66 of the Implement ECM. Connector contact 2 returns power to connector contact J1-55 of the Implement ECM.
The steering pilot supply solenoid acts as a On/Off solenoid. When all conditions are met, the Implement and Machine ECMs send a PWM Driver signal to the steering pilot supply solenoid and remote steering supply solenoid. The pilot solenoid supplies pilot pressure to the primary steering solenoids.
The electro-hydraulic (EH) steering system is used on remote control operation. The Implement Electronic Control Module (ECM) and the Machine ECM work together to provide a primary steering system and a secondary steering system.
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| Illustration 7 | g06097488 |
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Components that are used for the electronic control of the primary steering system and the secondary steering system (1) Implement ECM (2) Steering control spool position sensor (3) Primary steer pressure sensor (4) Secondary steer flow switch (5) Pilot steering pressure sensor (6) Remote steering supply solenoid (7) Right steering solenoid (8) Left steering solenoid (9) Steering cylinder position sensors (10) Operator present | |
The machines are equipped with an electro-hydraulically controlled steering system for remote control operation. The Implement ECM (1) works to provide a primary and secondary steering system when on remotes.
The Implement ECM communicates over the data links. The ECMs use the CAN A Data Link or CAN B Data Link as the primary data links. In the case of a failure, the ECMs will use the Cat Data Link as a backup.
The ECM monitors pilot steer manifold pressure sensor (5) steering position sensors. Implement ECM (1), also monitors steering cylinder position sensors (9), and if the operator is present (10). These inputs are used for steering (articulating) the machine when either the primary steering system is active or when the secondary steering system is active.
Implement ECM (1) also monitors steering control spool position sensor (2). Implement ECM (1) uses steering control spool position sensor (2), along with steering cylinder position sensors (9), to ensure the machine articulates in the desired direction. Steering pump pressure sensor (3) and secondary steering flow switch (4) also provide input to Implement ECM (1) for the secondary steering pump.
Implement ECM (1) sends current to steering pilot solenoid (6) and to left and right primary steering solenoids (7) and (8). The primary steering solenoids are used to articulate the machine.
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| Illustration 8 | g06292585 |
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Remote operator console (11) Steering/Direction control (12) Low idle/High idle switch | |
The Implement ECM uses signals from the operator console for steering/directional control (11).
Steering/Directional control (11) is used to steer the machine and change direction (forward, neutral, or reverse). The top of the control is Engine Revs Up/Down switch (12). When steering/directional control (11) is being used to move the machine and released to center, the transmission will automatically shift to neutral and the service brakes will apply.
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| Illustration 9 | g06131427 |
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(1) Connector view from ECM side
(2) Connector view from harness side | |
The ECM bases decisions on input information and memory information. After the 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 70 contact connectors (J1 and J2). The inputs and outputs to the ECM can be viewed through the Caterpillar Electronic Technician (Cat ET).
In most instances when a diagnostic code or an event code is activated, the ECM is the least likely cause of the problem. When an ECM is suspected to have failed, always ensure that the latest software is flashed on the ECM. Verify that the ECM connections are secure. Then, verify that the problem is still active before replacing an ECM
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.
| Implement ECM Connector J1 Contact Descriptions(1) | ||
|---|---|---|
| No. | Type | Function |
| 37 | PWM Input | Steering Valve Spool Position Sensor |
| 54 | Sourcing Driver Return | Remote Steer Solenoid Return |
| 55 | Sourcing Driver Return | Steer Pilot Supply Solenoid Return |
| 66 | Sourcing Driver Output | Steer Pilot Oil Supply Solenoid |
| 67 | Sourcing Driver Output | Remote Left Steer Solenoid |
| 68 | Sourcing Driver Output | Remote Right Steer Solenoid |
| (1) | System-specific pin locations |
| Implement ECM Connector J2 Contact Descriptions | ||
|---|---|---|
| No. | Type | Function |
| 5 | Sourcing Driver Output | Remote Steer Supply Solenoid |
| 8 | Sourcing Driver Return | Remote Steer Supply Solenoid Return |
| 34 | PWM Input | Pilot Steer Manifold Pressure Sensor |
| 35 | PWM Input | Primary Steer Pressure Sensor |
| 38 | Switch to Ground Input | Secondary Steer Flow Switch |
| 40 | PWM Input | Steering Cylinder Position Sensor |
| 41 | PWM Input | Steering Cylinder Position Sensor |
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 1 through 3.
- Pilot Steering Manifold Pressure Sensor
- Primary Steering Pressure Sensor
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| Illustration 10 | g06235947 |
The pressure sensor sends a PWM signal to the Implement ECM indicating system pressure. The duty cycle of the signal will vary in proportion to the system pressure. These PWM signals are inputs to the Implement ECM.
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| Illustration 11 | g06193992 |
The sensor is designed to communicate to the ECM the position of the steering control spool. The sensor generates an analog voltage signal.
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| Illustration 12 | g06235950 |
A rigid wire made of magnetostrictive material extends the length of the sensor rod to form a wave guide. At time zero, a current pulse is transmitted down the wire by the electronics in the head of the sensor. When the magnetic field surrounding the current in the wire reaches the magnetic target, a mechanical pulse is generated. The mechanical pulse travels back down the wave guide and is picked up by the sensor electronics. The total time is measured and converted into a PWM duty cycle.
The sensor is designed to communicate with the ECM, the position of the cylinder. The duty cycle of the signal varies in proportion to the position of the lever. The ECM receives the PWM signal. Then, the ECM measures the duty cycle to determine the position of the lever.
The Implement and Machine ECMs respond to decisions by sending electrical signals to the outputs. The outputs can create an action or the outputs can provide information to the operator or the service technician. The outputs of the Implement and Machine ECMs are listed in Tables1,2, and 3.
- Steering Pilot Supply Solenoid
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| Illustration 13 | g03566530 |
The steering pilot supply solenoid valve is an output of the Implement ECM. The Implement ECM energizes the steering pilot supply solenoid with approximately +24 DCV. Pressure oil will pass through the steering pilot supply solenoid valve when the steering pilot supply solenoid is energized. The steering pilot supply solenoid valve sends oil pressure to the STIC steering pilot valve.
The steering pilot supply solenoid has a connector with two contacts. Connector contact 1 of steering pilot supply solenoid receives power from connector contact J1-66 of the Implement ECM. Connector contact 2 returns power to connector contact J1-55 of the Implement ECM.
The steering pilot supply solenoid acts as a On/Off solenoid. When all conditions are met, the Implement ECM sends a PWM Driver signal to the steering pilot supply solenoid and remote steering supply solenoid. The pilot solenoid supplies pilot pressure to the STIC steering pilot control valve.
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| Illustration 14 | g06266153 |
The remote control steering pilot supply solenoid valve is an output of the Implement ECM. The Implement ECM energizes the remote control steering pilot supply solenoid with approximately +24 DCV. Pressure oil will pass through the remote control steering pilot supply solenoid valve when the remote control steering pilot supply solenoid is energized. The remote steering pilot supply solenoid valve sends oil pressure to the steering solenoids.
The remote steering pilot supply solenoid has a connector with two contacts. Connector contact 1 of remote steering pilot supply solenoid receives power from connector contact J2-5 of the Implement ECM. Connector contact 2 returns power to connector contact J2-8 of the Implement ECM.
The remote control steering pilot supply solenoid acts as a On/Off solenoid. When all conditions are met, the Machine and Implement ECM's send a PWM Driver signal to the remote control steering pilot supply solenoid and steering pilot supply solenoid. The remote steering pilot solenoid supplies pilot pressure to the steering solenoids.
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| Illustration 15 | g03566528 |
The remote left steering solenoid valve is an output of the Implement ECM. The Implement ECM energizes the remote left steering solenoid with approximately +24 DCV. Pressure oil will pass through the remote left steering solenoid valve when the remote left steering solenoid is energized. The remote left steering solenoid valve sends oil pressure to the directional spool.
The remote left steering solenoid has a connector with two contacts. Connector contact 1 of remote left steering solenoid receives power from connector contact J1-67 of the Implement ECM. Connector contact 2 returns power to connector contact J1-54 of the Implement ECM.
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| Illustration 16 | g03566528 |
The remote right steering solenoid valve is an output of the Implement ECM. The Implement ECM energizes the remote right steering solenoid with approximately +24 DCV. Pressure oil will pass through the remote right steering solenoid valve when the remote right steering solenoid is energized. The remote right steering solenoid valve sends oil pressure to the directional spool.
The remote right steering solenoid has a connector with two contacts. Connector contact 1 of remote right steering solenoid receives power from connector contact J1-68 of the Implement ECM. Connector contact 2 returns power to connector contact J1-54 of the Implement ECM.
The Cat Data Link is an input/output of the ECM. The data link uses the connector for the service port 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 J1-10 (wire 893-GN(Green)) and contact J1-20 (wire 892-BR(Brown)).
- The ECM receives commands from the Cat ET 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.
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. A data link is also required for instrument clusters and other devices that use service tool (Cat ET) communications protocol. The data link is not used to broadcast any diagnostic information.