| |
| Illustration 1 | g03018337 |
The Auxiliary ECM determines actions that are based on input information and memory information. After the Auxiliary 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 one 70 contact connector. 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.
In order 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 resister.
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
In order 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(1) | ||
| No.(2) | Type | Function |
| 1 | Battery + | + Battery |
| 2 | Battery - | - Battery |
| 3 | Key Switch | Key Switch |
| 7 | STG/STB | Harness Code 1 (Ground) |
| 8 | STG/STB | Harness Code 2 (Ground) |
| 10 | Supply Enable | Winch Pilot Supply |
| 11 | Driver On/Off Low side | Winch Brake Solenoid |
| 12 | Driver On/Off Low side | Winch Drive Away Lamp |
| 13 | Driver On/Off Low side | Winch Free Spool Lamp |
| 14 | Battery + | + Battery |
| 15 | Battery - | - Battery |
| 16 | Switch to Ground Return | Switch Return |
| 19 | STG/STB | Harness Code (Ground) |
| 21 | STG/STB | Winch Filter Bypass Switch |
| 24 | Battery + | + Battery |
| 25 | Battery - | - Battery |
| 26 | Driver High Side | Reel In Solenoid Supply |
| 27 | Driver Low Side | Reel In Solenoid Return |
| 28 | PWM/Frequency Sensor | Winch Pressure Sensor |
| 29 | PWM/Frequency Sensor | Ripper/Winch Auxiliary Lever |
| 32 | Driver High Side | Reel Out Solenoid Supply |
| 33 | Driver Low Side | Reel Out Solenoid Return |
| 34 | Driver High Side | Free Spool Solenoid Supply |
| 35 | Driver Low Side | Free Spool Solenoid Return |
| 37 | Active/Passive Input | 4th Valve Switch Extend |
| 38 | Active/Passive Input | 4th Valve Switch Retract |
| 39 | Active/Passive Input | 4th Valve Switch Parity |
| 44 | Active/Passive Input | Winch Drive Away Switch (N/C) |
| 45 | Active/Passive Input | Winch Drive Away Switch (N/O) |
| 46 | Active/Passive Input | Winch Free Spool Switch (N/C) |
| 47 | Active/Passive Input | Winch Free Spool Switch (N/O) |
| 55 | Sensor Return | Winch Pressure Sensor Return |
| 58 | Driver High Side | Drive Away Solenoid Supply |
| 59 | Driver Low Side | Drive Away Solenoid Return |
| 64 | Can A+ | CAN A Data Link + |
| 65 | Can A- | CAN A Data Link - |
| 68 | Sensor Power | Winch Pressure Sensor Supply |
| (1) | The ECM responds to an active input only when all of the necessary conditions are satisfied. |
| (2) | The connector contacts that are not listed are not used. |
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.
| |
| Illustration 2 | g01643136 |
Note: A machine can have a winch with a fourth function.
The sensor is designed to tell the ECM the position of the lever continuously. The lever for the winch has three ranges: REEL IN, HOLD and REEL OUT. The operator selects the range and the sensor sends the signal to the ECM. The sensor is a pulse width modulated sensor (PWM) and the sensor is an input of the ECM. The sensor generates a PWM signal continuously. 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 in order to determine the position of the winch lever. The frequency of this signal is approximately 500 Hz. The machine electrical system provides 10 V to the sensor for operating power.
| |
| Illustration 3 | g01339834 |
When the winch is in the brake mode, little pressure should be present in the drive loop. After the brake for the winch is applied, the sensor determines if high pressure is in the line. The sensor allows the ECM to determine the pressure differential across the motor ports of the winch.
Switches provide an open signal, a ground signal, or a +battery signal to the inputs of the ECM. Switches are open or closed.
- When a switch is open, no signal is provided to the corresponding input of the ECM. This “no signal” condition is also called “floating”.
- When a switch is closed, a ground signal or a +battery signal is provided to the corresponding input of the ECM.
| |
| Illustration 4 | g03731316 |
The implement lockout switch is designed to control the implement lockout solenoid. The ECM will provide power to the solenoid. The switch is a two pole momentary switch. When the machine is started, the implement lockout switch is engaged. Use the switch to toggle between LOCKED and UNLOCKED. The ECM disengages the implement lockout solenoid when the switch is placed in the LOCKED position. The switch should be in the LOCKED position before any of the following conditions occur:
- The operator exits the machine.
- The machine is serviced.
- The machine is left unattended.
The switch affects the system in the following manner:
LOCKED - The implement lockout solenoid is de-energized. The implement system is no longer operable.
UNLOCKED - The implement lockout solenoid is energized. The implement system is enabled.
The switch is a two pole switch. The switch has a normally closed contact and a normally open contact. The ECM can always determine whether the switch is in the LOCKED position or the UNLOCKED position. The two input circuits are used for diagnostic purposes. The ECM will detect a failure in the circuit if the two circuits of the switch are ever in the same state. The ECM will also record a diagnostic code.
| |
| Illustration 5 | g03794659 |
Push the switch in order to release the winch cable. The winch cable unreels by manually pulling the winch cable. Machine or hydraulic assistance is not needed. The winch will remain in the FREE SPOOL position until the switch is pressed again or until any other function of the winch is activated.
Note: Activating the switch allows the spool to move without tension on the cable. The cable can become tangled when the cable is allowed to move without tension applied to the cable.
| |
| Illustration 6 | g03794663 |
Push the DRIVE AWAY switch in order to release the winch brake. This function will also activate the DRIVE AWAY solenoid. When the drive away solenoid is energized, the solenoid valve sends pilot hydraulic pressure to the drive away valve. The drive away valve opens, which connects the motor ports together and allows the motor to turn independently of the closed circuit hydraulic pump. The resistance of the motor is then seen from the spool. As speed increases past an “over speed” point the resistance is increased through a Hydromechanical valve. The load will begin to drag behind the machine and limit the reel out speed. Tension is held on the cable in order to prevent the cable from becoming tangled. When the drive away solenoid is not energized, the valve is closed by a spring. The hydraulic flow from the closed circuit hydraulic pump may flow to the motor parts for the winch as required for the reel-in and the reel-out functions.
| |
| Illustration 7 | g03795643 |
The winch pilot shutoff solenoid valve is an On/Off type of solenoid valve. The winch pilot shutoff solenoid valve is designed to prevent the movement of the winch. If equipped with a winch, the winch pilot shutoff solenoid is connected to the implement lockout switch. When the implement lockout switch it deactivated, a signal is sent to the winch pilot shutoff solenoid.
The solenoid affects the system in the following manner:
LOCKED - The winch pilot shutoff solenoid is de-energized. The winch system is no longer operable.
UNLOCKED - The winch pilot shutoff solenoid is energized. The winch system is enabled.
| |
| Illustration 8 | g01383095 |
|
Winch spool in solenoid Winch spool out solenoid Winch free spool solenoid Winch drive away solenoid | |
Each of these solenoids is designed to control pilot pressure to the corresponding winch movement system. The ECM will adjust the solenoid valves according to the request that is made by the operator through the winch controls. These solenoid valves are the proportional type of solenoid valve. The ECM uses a pulse width modulated signal (PWM) in order to vary the current to the solenoid. The solenoid receives electrical current from the ECM. The solenoid plunger then travels a distance that is in proportion to the electrical current that is sent from the ECM. The electrical current to the solenoid controls the position of the valve. The ECM can detect a failure in the solenoid circuit and the ECM records a diagnostic code when a failure is present.
Note: Winch freespool and drive away are proportional solenoid valves, but are used in a ON/OFF control method.
Electronic communication between the Machine Control ECM, the Auxiliary 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 two types of data link systems.
- Cat Data Link
- SAE J1939 (CAN) Data Link
The two types of data links are the main structure for communication between all of the control modules on the machine.
The SAE J1939 Data Link circuit is mostly used for faster operational communication between the control modules on the machine. The Cat Data Link is used for some of the internal communication that does not require the faster speeds and is used for communication with external devices such as the Caterpillar Electronic Technician (Cat ET) service tool.
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 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 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.