Electronic Control Module (ECM)
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| Illustration 1 | g03032197 |
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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).
| Implement ECM Connector J1 Contact Descriptions(1) | ||
|---|---|---|
| No. | Type | Function |
| 1 | Keyswitch | Keyswitch |
| 10 | Cat Data Link (+) | Data Link |
| 12 | Sourcing Driver Output | Implement Pilot Supply Solenoid |
| 13 | Battery (-) | Battery (-) |
| 20 | Cat Data Link (-) | Data Link |
| 21 | Sensor Power Return | 5V Return |
| 22 | Analog Input | Hydraulic Oil Temperature |
| 23 | Battery (-) | Battery (-) |
| 28 | Switch to Ground Input | Location Code 4 (Grounded) |
| 31 | Battery (+) | Battery (+) |
| 32 | Switch to Ground Input | Location Code Enable (Grounded) |
| 33 | Switch to Ground Input | Implement Lockout Switch (N/O) |
| 34 | Switch to Ground Input | Implement Lockout Switch (N/C) |
| 39 | Battery (+) | Battery (+) |
| 41 | Switch to Ground Input | Joystick Trigger (N/O) |
| 42 | Switch to Ground Input | Joystick Trigger (N/C) |
| 44 | Sensor Power Output | 8 V Sensor Power |
| 45 | Sensor Power Return | 8 V Sensor Return |
| 47 | Battery (+) | Battery (+) |
| 48 | Sourcing Driver Output | Raise Solenoid |
| 49 | Sourcing Driver Output | Lower Solenoid |
| 50 | Sourcing Driver Return | PWM Driver 1-4 Return |
| 51 | Sourcing Driver Output | Left Tilt Cylinder Extend Solenoid |
| 52 | Sourcing Driver Output | Left Tilt Cylinder Retract Solenoid |
| 55 | Sourcing Driver Return | PWM Driver 9-12 Return |
| 56 | Sensor Power Return | 10 V Sensor Return |
| 57 | Battery (-) | Battery (-) |
| 60 | Sourcing Driver Return | PWM Driver 5-8 Return |
| 61 | Sourcing Driver Output | Right Tilt Cylinder Extend Solenoid |
| 62 | Sourcing Driver Output | Right Tilt Cylinder Retract Solenoid |
| 69 | Sensor Power Output/Sourcing Driver Output | 10 V Sensor Power |
| 70 | Battery (-) | Battery (-) |
| (1) | System-specific pin locations |
| Implement ECM Connector J2 Contact Descriptions(1) | ||
| No. | Type | Function |
| 1 | Battery (+) | Battery (+) |
| 4 | Sourcing Driver Return | 2A ON/OFF Return 1-3 |
| 24 | PWM Input | Joystick Lift Position Sensor |
| 25 | PWM Input | Joystick Tilt Position Sensor |
| 26 | PWM Input | Joystick Thumb Rocker Position Sensor |
| 36 | Switch to Ground Input | Case Drain Filter Bypass |
| 37 | Switch to Ground Input | Hydraulic Pilot Supply |
| 51 | PWM Input | Implement Pump Pressure Sensor |
| 56 | CAN Data Link (+) | CAN A HIGH |
| 67 | CAN Data Link (+) | CAN A HIGH |
| 68 | CAN Data Link (-) | CAN A LOW |
| 70 | CAN Data Link(-) | CAN A LOW |
| (1) | System-specific pin locations |
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.
Hydraulic Oil Temperature Sensor
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| Illustration 2 | g03372378 |
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Hydraulic Oil Temperature Sensor | |
The temperature sensor for the hydraulic oil informs the ECM of the temperature of the hydraulic system oil.
The sensor is designed internally to change resistance based on the temperature of the hydraulic oil. The Implement ECM uses up a pull resistor to receive sensor voltage and convert the voltage to a temperature reading. The resistance range for this sensor is 33,650 ohms at
- Main Hydraulic Valve Supply Pressure Sensor
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| Illustration 3 | g02571841 |
The main hydraulic valve supply 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.
Lift/Tilt Lever Position Sensor
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| Illustration 4 | g06058712 |
The joystick lift position sensor sends a Pulse Width Modulated (PWM) signal to the Implement ECM indicating the position of the lift control lever. The position sensor is located in the base of the joystick.
When the operator moves the joystick, the Implement ECM analyzes the signal from the joystick position sensor. The Implement ECM uses the sensor information, along with other conditions, to control the implement valve solenoids.
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| Illustration 5 | g03015758 |
The Implement ECM controls the operation of the Implement Pilot Supply Solenoid according to the position of the Hydraulic Lockout Switch. Certain fault conditions will also cause the Implement ECM to use the solenoid valve to disable hydraulic operation.
When the switch is in the UNLOCK position, the normally closed switch contacts will ground the input circuit at ECM contact J1-34 and J1-33 is opened. When the ECM detects this grounded circuit, the ECM will energize the implement pilot supply solenoid. The energized solenoid allows pilot oil to be supplied to the implement control valve.
When the switch is in the LOCK position, the normally open switch contacts will ground the input circuit at ECM contact J1-33 and J1-34 is opened. When the ECM detects this grounded circuit, the ECM de-energizes the ON/OFF output for the Implement Pilot Supply Solenoid. Pilot oil is blocked from the implement control valve.
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| Illustration 6 | g03015918 |
The bypass switch is a pressure switch that shows whether the filter is plugged and the filter is being bypassed. The oil filter bypass switch is a normally closed switch activating at
This switch is one of the inputs that is used to drive the "system indicator" in the instrument cluster. This indicator is turned ON when the switch is in the closed position and the oil temperature is greater than
The 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 ECM are listed in tables .
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| Illustration 7 | g06058780 |
The lift/tilt solenoids control the flow of pilot oil to the lift/tilt valve spools for shifting the valve spools. The lift/tilt valve spools control the flow of hydraulic oil to the lift/tilt cylinders. The ECM sends a PWM driver to the lift/lower solenoids to allow more or less flow of pilot oil through the solenoid valves. The PWM driver sent to the lift/tilt solenoids is based on the input signal from the operator lift/tilt control and thumb rocker.
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 Transmission Electronic Control Module is 051. The MID for the Implement Electronic Control Module is 052.
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 communications protocol. The data link is not used to broadcast any diagnostic information.