Electronic Control Module (ECM)
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 machine ECM are connected to the machine harness by two 70 contact connectors (J1 and J2).
The machine ECM input component is as follows:
- Hydraulic temperature sensor
The inputs and outputs of the engine ECM are connected to the engine harness by two 64 contact connectors (J1 and J2). The inputs and outputs to the engine ECM can be viewed through the Caterpillar Electronic Technician (Cat ET).
The engine ECM controls the reversing of the fan. Engine ECM input and output components are as follows:
- Reversing fan speed solenoid
- Inlet manifold temperature (IMT) sensor
- Photo tach fan speed sensor
The inputs and outputs of the fan control ECM are connected to the engine harness by a 12 contact connector. The inputs and outputs to the fan control ECM can be viewed through the Caterpillar Electronic Technician (Cat ET).
The fan control ECM controls the fan speed. Engine ECM output components are as follows:
- Demand fan solenoid
The fan speed is driven by coolant temperature and the input with the highest requirement of cooling.
The demand fan solenoid valve controls the speed of the fan. The demand fan solenoid valve allows the speed of the fan to decrease in cool ambient temperature or in a light work application. The demand fan valve is controlled by the transmission ECM. Engine ECM will interpret the data from the two sensors and will send a change in current to transmission ECM. The fan control ECM will send the command to demand fan speed solenoid. Adjustment to fan speed should be done using the fan calibration screen in Electronic Technician.
After the hydraulic oil exits hydraulic fan gear motor, the oil flows through a hydraulic oil line to hydraulic oil cooler). Hydraulic oil cooler bypass valve limits the maximum oil pressure in hydraulic oil cooler
Machine Electronic Control Module (ECM)
| |
| Illustration 1 | g06039271 |
|
Machine ECM Shown (1) ECM J1 Connector (2) ECM J2 Connector | |
| |
| Illustration 2 | g03701995 |
|
Implement ECM Pinouts | |
Engine Electronic Control Module (ECM)
| |
| Illustration 3 | g06039172 |
|
Engine ECM Shown (1) ECM J1 Connector (2) ECM J2 Connector | |
| |
| Illustration 4 | g06039182 |
|
Engine ECM Pinouts | |
| |
| Illustration 5 | g06046458 |
|
Fan Control ECM Shown (1) ECM Connector | |
| |
| Illustration 6 | g06046481 |
|
Fan Control ECM Pinouts | |
| Machine ECM Connector J1 Contact Descriptions(1) | ||
|---|---|---|
| Number | Type | Function |
| 21 | Sensor Power Return | 5 V Return |
| 22 | Analog Input | Hydraulic Oil Temperature |
| (1) | System-specific pin locations |
| Machine ECM Connector J2 Contact Descriptions(1) | ||
|---|---|---|
| Number | Type | Function |
| 67 | CAN Data Link (+) | CAN (A) Data Link (+) |
| 68 | CAN Data Link (-) | CAN (A) Data Link (-) |
| (1) | System-specific pin locations |
| Engine ECM Connector J1 Contact Descriptions(1) | ||
|---|---|---|
| Number | Type | Function |
| 4 | Analog Input | Air Inlet Temperature |
| 13 | Digital Input | Photo Tach Fan Speed Sensor |
| 20 | CAN Data Link (+) | CAN (A) Data Link (+) |
| 21 | CAN Data Link (-) | CAN (A) Data Link (-) |
| 26 | Analog Output | Reversing Fan Solenoid |
| 32 | Analog Input | Reversing Fan solenoid |
| 33 | Sensor Power Return | 5 V Return |
| 34 | Analog Output | Air Inlet Temperature |
| 40 | Key Switch Input | Key Switch |
| 41 | Sensor Power Output | Photo Tach Fan Speed Sensor |
| (1) | System-specific pin locations |
| Fan Control ECM Connector Contact Descriptions(1) | ||
|---|---|---|
| Number | Type | Function |
| 4 | PWM Output | Demand Fan Speed Solenoid (A) |
| 6 | PWM Output | Demand Fan Speed Solenoid (B) |
| 7 | Battery Power Input | Battery Positive |
| 8 | Battery Return | Battery Negative |
| 10 | CAN Data Link (+) | CAN (A) Data Link (+) |
| 11 | CAN Data Link (-) | CAN (A) Data Link (-) |
| (1) | System-specific pin locations |
Electronic Control Module (ECM)
The Engine ECM bases decisions on input information and memory information. After the Engine 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 64 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 of failure, 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.
The machine has several different types of input devices. The ECM receives machine status information from the inputs devices and determines the correct output action that is needed in order to control machine operations based on memory and software parameters. the machine utilizes the following types of inputs: switch type and sensor type.
Switches provide signals to the switch inputs of the ECM. The possible outputs of a switch are listed: an open signal, a ground signal and + battery signal.
Sensors provide an electrical signal to the ECM that constantly changes. The sensor input to the ECM can be one of several different types of electrical signals such as: pulse width modulated (PWM) signals, voltage signals, and frequency input signals. Each possible input to the ECM is listed in the tables
| |
| Illustration 7 | g03832074 |
The reversing fan can be enabled or disabled using Cat ET. By default the reversing fan is enabled. If the reversible fan switch is pressed, the light will blink and the engine ECM will engage the reverse mode for the fan. If the light is solid, the fan is in "Auto" mode and the fan will reverse for a predetermined time on a set interval. The reversing fan intervals are also adjustable using Cat ET.
| |
| Illustration 8 | g01113896 |
The temperature sensor is a passive analog sensor. The signal voltage of the sensor corresponds to the temperature of the hydraulic oil. The voltage signal is an input to the Machine ECM. This voltage signal will vary representing changes in the hydraulic oil temperatures. The temperature of the sensor is displayed on the instrument cluster. The temperature is represented in either Metric units or English units. The temperature is accessible by scrolling through the display.
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.
| |
| Illustration 9 | g02747758 |
|
Typical example of a solenoid valve (1) Pin 1 (2) Pin 2 | |
Demand Fan Proportional Solenoid Valve
The demand fan proportional solenoid valve is located on the bottom side of the fan motor housing. The demand fan proportional solenoid valve receives a variable PWM signal from the fan control ECM based on the machine temperature sensor inputs.
Demand Fan Reversing Solenoid Valve
The demand fan reversing solenoid valve is located on the top side of the fan motor housing. The demand fan reversing solenoid can be operated manually or automatically. In manual mode, the operator chooses when to reverse the fan by pressing the reversing fan button on the keypad in the cab. In automatic mode the fan control ECM will reverse the fan for 10 seconds every 30 minutes.
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. 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 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 as well as instrument clusters and other devices that use this communications protocol. The data link is not used in order to broadcast any diagnostic information.
On most Cat machine models, there is more than one CAN system. These CAN systems are used to conduct high-speed operational data transfer between control modules. Some components also now use the CAN data link to send input signals to the ECM.