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 Implement ECM bases decisions 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 inputs and outputs to the ECM can be viewed through the Caterpillar Electronic Technician (Cat ET).
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.
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
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.
The Cat Data Link is used to provide a connection for the service tool for troubleshooting, testing, and calibrations. The data link is bidirectional. The data link allows the ECM to receive information. The data link also allows the ECM to send information.
| Implement ECM ConnectorJ1
Contact Descriptions(1) |
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|---|---|---|
| No. | Type | Function |
| 1 | Key Switch Input | Key Switch Run |
| 10 | CAN C Data Link - | CAN C Data Link - |
| 11 | Sensor Power Output | +5 Sensor Supply |
| 12 | Sourcing Driver Output | Winch Accumulator SOL |
| 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 - |
| 27 | Switch to Ground Input | Location Code 1 |
| 31 | Battery Power Input | Battery + |
| 32 | Switch to Ground Input | Location code Enable |
| 33 | Switch to Ground Input | Single/Dual Tilt Trigger SW (N/C) |
| 34 | Switch to Ground Input | Single/Dual Tilt Trigger SW (N/O) |
| 35 | Switch to Ground Input | Blade Manual Select SW (N.C.) |
| 38 | Battery Power Input | Battery + |
| 39 | Battery Power Input | Battery + |
| 40 | Switch to Ground Input | Blade Manual Select SW (N.O) |
| 41 | Switch to Ground Input | Blade Mode Select SW (N.C) |
| 42 | Switch to Ground Input | Blade Mode Select SW (N.O.) |
| 43 | Switch to Ground Input | Hyd Tank Pressure SNSR |
| 44 | Sensor Power Output | +8V Power |
| 45 | Sourcing Driver Output | +8V Return |
| 47 | Battery Power Input | Battery + |
| 48 | Sourcing Driver Output | Blade Raise Solenoid |
| 49 | Sourcing Driver Output | Blade Lower Solenoid |
| 50 | Sourcing Driver Return | Blade Solenoid Return |
| 51 | Sourcing Driver Output | Blade Tilt Left Solenoid |
| 52 | Sourcing Driver Output | Blade Tilt Right Solenoid |
| 54 | Sourcing Driver Return | Quick Drop Solenoid Return |
| 55 | Sourcing Driver Return | PWM DR Ret 9–12 |
| 56 | Sensor Power Return | 10V Return |
| 57 | Battery Return | Battery - |
| 58 | Sourcing Driver Output | Rip Raise/Winch Brk Off |
| 59 | Sourcing Driver Output | RIP LWR/WINCH FREE SPL |
| 60 | Sourcing Driver Return | Pwm Dr Ret |
| 61 | Sourcing Driver Output | Blade Angle Right |
| 62 | Sourcing Driver Output | Blade Angle Left |
| 63 | Switch to Ground Input | Ripper Autostow SW (N/C) |
| 64 | Switch to Ground Input | Ripper Autostow SW (N/O) |
| 65 | Sourcing Driver Output | Winch Reel In Sol |
| 66 | Sourcing Driver Output | Winch Reel Out Sol |
| 67 | Sourcing Driver Output | Ripper Hyd Oil Blocking Sol |
| 68 | Sourcing Driver Output | Quick Drop Sol |
| 69 | Sensor Power Output | 10V Power |
| 70 | Battery Return | Battery - |
| (1) | Contacts that are not listed are not used. |
| Implement ECM Connector J2
Contact Descriptions(1) |
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|---|---|---|
| No. | Type | Function |
| 1 | Switch to Battery Input/Sourcing Drv Enable | Battery (Switched) |
| 2 | Sourcing Driver Output | Implement Shutoff SW Common (Pin2 Pole 1) |
| 3 | Sourcing Driver Output | Boost Sol |
| 4 | Sourcing Driver Return | Implement Shutoff Solenoid Return |
| 5 | Sourcing Driver Output | Winch System Flow Solenoid |
| 6 | Sourcing Driver Output | PT Pump Bypass Solenoid |
| 8 | Sourcing Driver Return | Boost/Diverter Solenoid |
| 22 | Return | Digital Return |
| 24 | PWM Input | Blade Raise/Lower Position Sensor |
| 25 | PWM Input | Blade Tilt Position Sensor |
| 26 | PWM Input | Blade Angle Position Sensor |
| 27 | PWM Input | Rip Raise/Lower/Aux /Winch |
| 28 | Switch to Ground Input | Winch Handle Pushbutton (N/C) |
| 29 | Switch to Ground Input | Winch Handle Pushbutton (N/O) |
| 30 | Switch to Ground Input | Seat Belt Switch |
| 31 | Switch to Ground Input | Seat Belt Switch |
| 32 | PWM Input | Aux X-Axis/Winch Y-Axis |
| 36 | Switch to Ground Input | Winch High Temp Signal |
| 37 | Switch to Ground Input | Winch Filter Plugged Signal |
| 38 | Switch to Ground Input | Winch Free Spool (N/C) |
| 39 | Switch to Ground Input | Winch Free Spool (N/O) |
| 42 | PWM Input | Main Pump Pressure |
| 44 | Switch to Ground Input | Winch Low Speed Lock (Turtle) |
| 45 | Switch to Ground Input | Winch Low Speed Lock (Rabbit) |
| 46 | Switch to Ground Input | Implement Shutoff SW (Pin 4 Pole2) |
| 47 | Switch to Ground Input | Implement Shutoff SW (Pin 6 Pole2) |
| 50 | PWM Input | Winch Temp SENSOR |
| 54 | Switch to Ground Input | Remote Control Enable |
| 55 | Switch to Ground Input | Remote Control Enable Parity |
| 64 | CAN Data Link (+) | CAN B+ |
| 65 | CAN Data Link (-) | CAN B- |
| 67 | CAN Data Link (+) | CAN A+ |
| 68 | CAN Data Link (-) | CAN A- |
| (1) | 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 Tank Temperature Sensor
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| Illustration 2 | g03446341 |
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.
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| Illustration 3 | g03346558 |
The main implement pump sensor is an active analog sensor. The sensor sends an output voltage that is proportional to the pressure of the main implement pump sensor.
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| Illustration 4 | g03347829 |
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| Illustration 5 | g06349281 |
The ECM receives signals from the blade control handle as pulse width modulated signals. These signals are operator requests for blade movement such as RAISE, LOWER, TILT LEFT, and TILT RIGHT. Usually, the ECM will respond to the duty cycle of the pulse width modulated signal by sending a corresponding pulse width modulated signal to the related solenoids. The ECM relates a specific sensor duty cycle value to a specific control handle position. The ECM determines the correct solenoid output based on a "software map" that is contained in the programmable memory of the ECM. The ECM receives signals from a position sensor on the X-axis and a position sensor on the Y-axis.
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| Illustration 6 | g03346395 |
The blade angle sensor is the proportional thumb rocker on the blade control handle. The sensor is an active pulse width modulated position sensor. The ECM interprets the pulse width modulated signal as a specific position on the thumb rocker. The thumb rocker controls the blade angle. A thumb rocker position to the left corresponds with a blade angle right movement.
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| Illustration 7 | g03376439 |
The ripper/winch control handle has two active pulse width modulated position sensors. One sensor detects winch spool in/out or ripper raise/lower and one sensor detects winch drum clutch release. The ECM interprets the pulse width modulated signals as specific positions on the spool in/out or ripper raise/lower and drum clutch controls. The ECM sends a corresponding pulse width modulated signal to the winch spool in/out and drum clutch solenoids.
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. The “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.
Hydraulic Tank Pressure Switch
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| Illustration 8 | g06267049 |
The pressure switch informs the ECM of system pressure. The contact floats to a high voltage when the switch is not closed. When the switch closes, the contact is pulled to a low or ground voltage state by the return line.
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| Illustration 9 | g06267022 |
The charge filter bypass switch is a pressure switch. The switch alerts the ECM when the charge filter is being bypassed. The contact floats to a high voltage when the switch is not closed. When the switch closes, the contact is pulled to a low or ground voltage state by the return line.
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| Illustration 10 | g06258762 |
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.
The ECM responds 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.
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| Illustration 11 | g06258855 |
All proportional solenoids in the implement system are identical in construction, however function differently. Illustration 11 shows an example of a proportional solenoid in the implement system.
Note: The solenoid coils are not designed to operate using 24 DCV directly. The ECM sends a PWM signal of 24 V at a duty cycle that will provide the necessary current to the solenoid coils. Do NOT activate the coils by using 24 DCV (+battery). The life of the coils will be reduced drastically. A source of 12 DCV should be used, if the coils must be activated by not using the ECM.
There are two solenoids controlling blade lift. There is a raise and lower solenoid. The solenoids are identical in construction, and together control the operation of the blade lift valve spool. The solenoids are proportional solenoids and depending on the duty cycle of the ECM outputs the lift spool will shift depending upon input.
There are two solenoids controlling blade tilt. There is a left tilt and right tilt solenoid. The solenoids are identical in construction, and together control the operation of the blade tilt valve spool. The solenoids are proportional solenoids and depending on the duty cycle of the ECM outputs the tilt spool will shift depending upon input.
There are two solenoids controlling ripper height. There is a ripper raise and lower solenoid. The two solenoids are identical in construction, and together control the operation of the ripper raise/lower spool. The solenoids are proportional solenoids, and if the ECM sends a higher duty cycle signal to the ripper raise solenoid, that solenoid shifts the spool further in the RAISE position. If the ECM sends a higher duty cycle signal to the ripper lower solenoid, that solenoid shifts the spool further in the LOWER position.
Quick Drop Solenoid (IF EQUIPPED)
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| Illustration 12 | g03447776 |
The quick drop solenoid is on/off type solenoid. The solenoid is activated by the ECM when the lever reaches 75 percent travel, which is before the float detent.
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| Illustration 13 | g06258988 |
The implement shutoff solenoid is energized by the implement shutoff switch. When the switch is energized, a circuit is completed allowing energy to flow to the implement lockout solenoid. The solenoid is an on/off type solenoid. When the solenoid is de-energized, the solenoid prevents the implement system from operating.
Electronic communication between the Implement ECM, Machine 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.