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| Illustration 1 | g03307257 |
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| Illustration 2 | g01309473 |
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ECM Connectors and Contacts | |
The Implement ECM determines actions that are based on input information and memory information. After the Implement ECM receives the input information, the ECM sends a corresponding response to the outputs. The inputs and outputs of the Implement ECM are connected to the machine harness by two 70 contact connectors (J1 and J2). The ECM sends the information to the Caterpillar Electronic Technician (Cat ET) on the Cat Data Link.
Note: The ECM is not serviceable. The ECM must be replaced if the ECM is damaged. Replace the ECM if a failure is diagnosed.
To aid in diagnostics of certain types of electrical circuits that are controlled by the ECM, an internal "pull up voltage" is connected to ECM switch and sensor signal input contacts. An above normal voltage is internally connected to the ECM signal input circuit through a resistor.
During normal operation, the switch or sensor signal will hold the circuit low or at a certain signal amplitude, however, circuit conditions such as a loss of power to the component, a disconnection, or an open circuit will allow the circuit to be pulled high by the ECM pull-up voltage. This condition will result in an above normal voltage condition at the ECM contact. As a result, the ECM will activate an FMI 03 (voltage above normal) diagnostic code for the affected circuit.
The types of ECM input circuits that have pull up voltage present are:
- Pulse Width Modulated (PWM) sensor input circuits
- Switch to Ground Input switch input circuits
- Active analog (voltage) input signal circuits
- Passive analog (resistance) input signal circuits
To aid in diagnostics of electrical circuits that are controlled by the ECM, an internal "pull down voltage" is connected to ECM switch to battery type input circuits.
During normal operation, the switch contacts that are allowing the connection to a voltage source will hold the circuit high. When circuit conditions such as a loss of power to the switch supply voltage, a disconnection in the switch circuit or an open circuit will allow the circuit to be pulled low by the ECM pull-down voltage. This condition will result in a below normal voltage condition at the ECM contact. As a result, the ECM will activate an FMI 04 (voltage below normal) diagnostic code for the affected circuit.
| Implement ECM Contact Description J1 Contact Descriptions(1) | ||
|---|---|---|
| No.(2) | Type | Function |
| 10 | CAN C Data Link - | CAN C Data Link - |
| 11 | Sensor Power Output | 5V Sensor Supply |
| 13 | Battery Return | Battery - |
| 20 | CAN C Data Link + | CAN C Data Link + |
| 21 | Sensor Power Return | 5V Sensor Return |
| 22 | Analog Input | Hydraulic Oil Temp Sender Temperature Sensor |
| 23 | Battery Return | Battery - |
| 31 | Battery Power Input | Battery + |
| 38 | Battery Power Input | Battery + |
| 39 | Battery Power Input | Battery + |
| 47 | Battery Power Input | Battery + |
| 56 | Sensor Power Return | 10V Return |
| 57 | Battery Return | Battery - |
| 69 | Sensory Power Output | 10V Sensor Supply |
| 70 | Battery Return | Battery - |
| (1) | Contacts that are not listed are not used. |
| (2) | The connector contacts that are not listed are not used. |
The machine has several different types of input devices. The ECM receives machine status information from the input devices and determines the correct output action that is needed 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 grounded 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 for the 70-pin connectors.
Inputs provide information to the ECM in the form of sensors or switches.
Sensors provide information to the ECM about the intent of the operator or changing conditions. The sensor signal changes proportionally to the changing of operator input or changing conditions. The following types of sensor signals are used by the ECM.
Frequency - The sensor produces a signal and the frequency (Hz) varies as the condition changes.
Pulse width modulated - The sensor produces a signal. The duty cycle of the signal varies as the condition changes. The frequency of this signal is constant.
Analog - The ECM measures the voltage that is associated to a specific condition of the control.
Hydraulic Oil Temperature Sensor
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| Illustration 3 | g06309007 |
The hydraulic oil temperature sensor is a passive analog sensor. The resistance of the sensor changes proportionally to temperature changes. The ECM measures the resistance of the sensor and determines the temperature of the hydraulic oil. If the ECM detects that the hydraulic oil has exceeded a preset temperature, the ECM sends a signal to the engine ECM to engage the hydraulic fan.
Electronic communication between the Implement ECM, Power Train ECM, Engine ECM, and the other control modules on the machine is conducted over data link circuits. The data link circuits allow the sharing of information with other electronic control modules. The data link circuits are bidirectional. The data link circuit allows the ECM to send information and to receive information.
The electronic communication system consists of multiple CAN datalink systems.
The SAE J1939 CAN Data Link circuit is separated into different groups. "CAN A" is connected to all the ECMs on the machine, and is used primarily for information and service purposes, such as the Caterpillar Electronic Technician (CAT ET). The other data link systems are high-speed data links used for machine control purposes.