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| Illustration 1 | g03307257 |
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(1) Transmission ECM
(2) J1 machine harness connector (3) J2 machine harness connector | |
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| Illustration 2 | g01309473 |
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ECM Connectors and Contacts | |
The Transmission ECM determines actions based on input information and memory information. After the Transmission ECM receives the input information, the ECM sends a corresponding response to the outputs. The Transmission ECM is linked to the Chassis ECM by a signal wire. Specific functions are controlled by the Chassis ECM based on the input from the Transmission ECM. The inputs and outputs of the Transmission ECM are connected to the machine harness by two 70 contact connectors (J1 and J2). The ECM sends the information to Cat® 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.
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| Illustration 3 | g03307257 |
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(1) Chassis ECM
(2) J1 machine harness connector (3) J2 machine harness connector | |
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| Illustration 4 | g01309473 |
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ECM Connectors and Contacts | |
The Chassis ECM determines actions that are based on input information and memory information. After the Chassis ECM receives the input information, the ECM sends a corresponding response to the outputs. The inputs and outputs of the Chassis ECM are connected to the machine harness by two 70 contact connectors (J1 and J2). The ECM sends the information to Cat® 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 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 3 (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 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 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 allow the circuit to be pulled low by the ECM pull-down voltage. This condition results in a below normal voltage condition at the ECM contact. As a result, the ECM will activate an FMI 4 (voltage below normal) diagnostic code for the affected circuit.
Transmission Module Pin Locations
| Transmission ECM J1 (MID 81) Contact Descriptions(1) | ||
|---|---|---|
| No.(2) | Description | Function/Type |
| 1 | Key Switch (ON) | ECM Power |
| 2 | Tacho + Runs To Tacho Engine (+) | Engine Speed (+) (Analog Passive) |
| 3 | Tacho 1 Runs To Tacho Engine (-) | Engine Speed (-) (Analog Passive) |
| 4 | Transmission Input Speed Sensor (+) | Transmission Input Speed (+) (Analog Passive) |
| 5 | Transmission Input Speed Sensor (-) | Transmission Input Speed (-) (Analog Passive) |
| 6 | Transmission Output Speed Sensor 1 (+) | Transmission Output Speed (+) (Analog Passive) |
| 7 | Transmission Output Speed Sensor 1 (-) | Transmission Output Speed (-) (Analog Passive) |
| 8 | Transmission Output Speed Sensor 2 (+) | Transmission Output Speed (+) (Analog Passive) |
| 9 | Transmission Output Speed Sensor 2 (-) | Transmission Output Speed (-) (Analog Passive) |
| 10 | Cat® Data Link (+) | Cat® Data Link (+) |
| 11 | (+) 5V Sensor Supply | Sensor Voltage Source (+) |
| 13 | Battery (-) | Voltage Return (-) |
| 15 | Transmission Intermediate Speed Sensor 1 (+) | Transmission Speed (+) (Analog Passive) |
| 16 | Transmission Intermediate Speed Sensor 1 (-) | Transmission Speed (-) (Analog Passive) |
| 17 | Transmission Intermediate Speed Sensor 2 (+) | Transmission Speed (+) (Not Used) |
| 18 | Transmission Intermediate Speed Sensor 2 (-) | Transmission Speed (-) (Not Used) |
| 20 | Cat® Data Link (-) | Cat® Data Link (-) |
| 21 | (+) 5V Sensor Supply Return | Sensor Voltage Return (-) |
| 23 | Battery (-) | Battery (-) |
| 26 | ECM Location Code 0 (Ground) | Ground |
| 27 | ECM Location Code (Ground) | Ground |
| 28 | ECM Location Code 2 (Open) | Open |
| 31 | Battery (+) | Battery (+) |
| 32 | ECM Location Code Enable (Ground) | ECM Location Enable |
| 35 | Transmission Oil Level Switch | Analog Active Sensor |
| 37 | Steering Valve Spool Position Sensor (AMT) | (Not Used) |
| 38 | Battery (+) | Battery (+) |
| 39 | Battery (+) | Battery (+) |
| 44 | (+) 8V Sensor Supply | Sensor Voltage Supply |
| 45 | (+) 8V Sensor Supply Return | Sensor Voltage Return |
| 46 | Battery (+) | Battery (+) |
| 47 | Battery (+) | Battery (+) |
| 48 | Transmission Clutch 1 Solenoid | Electronic Clutch Pressure Control 1 |
| 49 | Transmission Clutch 3 Solenoid | Electronic Clutch Pressure Control 3 |
| 50 | Proportional Driver Solenoid Return (1-4) | Sourcing Driver Return |
| 51 | Transmission Clutch 5 Solenoid | Electronic Clutch Pressure Control 5 |
| 52 | Transmission Clutch 7 Solenoid | Electronic Clutch Pressure Control 7 |
| 54 | Proportional Driver Solenoid Return (11-12) | Sourcing Driver Return |
| 55 | Proportional Driver Solenoid Return (9-12) | Sourcing Driver Return |
| 56 | (+) 10V Sensor Supply Return | Sensor Voltage Return |
| 57 | Battery (-) | Battery (-) |
| 58 | Transmission Clutch 2 Solenoid | Electronic Clutch Pressure Control 2 |
| 59 | Transmission Lockup Clutch Solenoid | Lockup Clutch Solenoid |
| 60 | Proportional Driver Solenoid Return (5-8) | Sourcing Driver Return |
| 61 | Transmission Clutch 4 Solenoid | Electronic Clutch Pressure Control 4 |
| 62 | Transmission Clutch 6 Solenoid | Electronic Clutch Pressure Control 6 |
| 67 | Secondary Steering Left Solenoid (AMT) | (Not Used) |
| 68 | Secondary Steering Right Solenoid (AMT) | Output |
| 69 | (+) 10V Sensor Supply | Sensor Voltage Supply |
| 70 | Battery (-) | Battery - |
| (1) | Contacts that are not listed are not used. |
| (2) | The connector contacts that are not listed are not used. |
| Transmission ECM (MID 81) Contact Description J2(1) | ||
|---|---|---|
| No.(2) | Description | Function/Type |
| 4 | Proportional Solenoid Return Feedback #3 | Sourcing Driver Return |
| 15 | (L) Steering Cylinder Spool Position Sensor (AMT) | (Not Used) |
| 16 | (R) Steering Cylinder Spool Position Sensor (AMT) | Pulse Width Modulated (PWM) Sensor |
| 18 | Joystick Test Input (AMT) | (Not Used) |
| 24 | Requested Gear Command | Data Link to Chassis ECM |
| 25 | Transmission Oil Temperature Sensor | Pulse Width Modulated (PWM) Sensor |
| 26 | Secondary Steering Request Signal | (Not Used) |
| 29 | Torque Converter Inlet Filter Bypass Switch | Pressure Actuated (Switch-to-Ground) |
| 30 | Torque Converter Screen Filter Switch | Pressure Actuated (Switch-to-Ground) |
| 33 | Torque Converter Outlet Oil Temperature Sensor | Pulse Width Modulated (PWM) Sensor |
| 34 | Transmission Charge Filter Bypass Switch | Pressure Actuated (Switch-to-Ground) |
| 42 | Transmission Lube Pressure Sensor | (Not Used) |
| 43 | Transmission Output Speed Sensor #2 (SIG A AMT) | (Not Used) |
| 48 | Transmission Output Speed Sensor #2 (SIG B AMT) | (Not Used) |
| 56 | Global CAN A Data Link (+) (Redundant Pin) | CAN A Data Link (+) |
| 61 | Product ID Master | Ground (-) |
| 63 | Ground (-) | Ground (-) |
| 64 | Local CAN B (+) | CAN B Data Link (+) |
| 65 | Local CAN B (-) | CAN B Data Link (-) |
| 66 | Local CAN B Shield | CAN B Shield |
| 67 | Global CAN A (+) (Main) | CAN A Data Link (+) |
| 68 | Global CAN A (-) (Main) | CAN A Data Link (-) |
| 69 | Global CAN A Shield (Main) | CAN A Shield |
| 70 | Global CAN A (-) (Redundant Pin)) | CAN A Data Link - |
| (1) | The ECM responds to an active input only when all the necessary conditions are satisfied. |
| (2) | The connector contacts that are not listed are not used. |
| Chassis ECM J1 (MID 87) Contact Descriptions(1) | ||
|---|---|---|
| No.(2) | Type | Function/Type |
| 1 | Key Switch (ON) | Battery (+) |
| 10 | Cat ®Data Link (+) | Cat® Data Link (+) |
| 11 | (+) 5V Sensor Supply | Sensor Voltage Supply (+) |
| 12 | Brake Accumulator Bleed Solenoid | Solenoid |
| 13 | Battery (-) | Battery (-) |
| 14 | Key Switch (OFF) | ECM Power (OFF) |
| 19 | CDL/CAN Shield | Shield |
| 20 | Cat® Data Link (-) | Cat® Data Link (-) |
| 21 | (+) 5V Sensor Supply Return | Sensor Voltage Return (-) |
| 23 | Battery (-) | Battery (-) |
| 25 | Headlight Switch | Ground |
| 26 | ECM Location Code 0 (Ground) | Ground |
| 27 | ECM Location Code 1 (Open) | Open |
| 28 | ECM Location Code 2 (Open) | Open |
| 31 | Battery (+) | Battery (+) |
| 32 | ECM Location Code Enable (Ground) | Ground |
| 34 | Hydraulic Case Drain Filter Bypass Switch | (Not Used) |
| 36 | System Air Pressure Sensor | Analog Active Sensor |
| 38 | Battery (+) | Battery (+) |
| 39 | Battery (+) | Battery (+) |
| 40 | Hydraulic Oil Level Sensor (Wiggins) | Analog Active Sensor |
| 41 | Top Drive Gear Select Decrement Switch | Pulse Width Modulated (PWM) Sensor |
| 42 | Top Drive Gear Select Increment Switch | Pulse Width Modulated (PWM) Sensor |
| 43 | Operator Seat Belt Switch | Switch Input |
| 44 | (+) 8V Sensor Supply | Voltage Sensor Supply (+) |
| 45 | (+) 8V Sensor Supply Return | Voltage Sensor Return (-) |
| 46 | Battery (+) | Battery (+) |
| 47 | Battery (+) | Battery (+) |
| 48 | Hoist Pump Bypass #1 Solenoid | (Not Used) |
| 49 | Hoist Pump Bypass #2 Solenoid | (Not Used) |
| 50 | Proportional Driver Return (1-4) | Sourcing Driver Return |
| 51 | Hoist Control to Tank Head Solenoid | (Not Used) |
| 52 | Hoist Control to Tank Rod Solenoid | (Not Used) |
| 54 | Proportional Driver Return (11-12) | Sourcing Driver Return |
| 55 | Proportional Driver Return (9-12) | Sourcing Driver Return |
| 56 | (+) 10V Sensor Supply Return | Voltage Sensor Return (-) |
| 57 | Battery (-) | Battery (-) |
| 58 | Hoist Pump to Control Head Solenoid | (Not Used) |
| 59 | Hoist Pump to Control Rod Solenoid | (Not Used) |
| 60 | PWM Driver Return (1-8) | Sourcing Driver Return |
| 61 | Steering Accumulator Charging Solenoid | Solenoid |
| 62 | Hoist Raise Solenoid | Solenoid |
| 64 | Steering Oil Level Sensor (Wiggins) | Analog Active Sensor |
| 65 | Hoist Lower Solenoid | Solenoid |
| 66 | Hoist Pilot System Enable Solenoid | (Not Used) |
| 67 | Auto Steer Enable Solenoid #2 | (Not Used) |
| 69 | (+) 10V Sensor Supply | Voltage Sensor Supply (+) |
| 70 | Battery (-) | Battery (-) |
| (1) | Contacts that are not listed are not used. |
| (2) | The connector contacts that are not listed are not used. |
| Chassis ECM (MID 87) Contact Description J2(1) | ||
|---|---|---|
| No.(2) | Type | Function/Type |
| 1 | Key Switch (Crank) | Engine Start Input |
| 2 | Brake Accumulator Bleed Solenoid (R) | Solenoid |
| 3 | Auto Lube Relay | Relay |
| 4 | Solenoid Return | Ground |
| 5 | Idle Shutdown Timer Relay | Relay |
| 6 | Steering Accumulator Bleed Solenoid | Solenoid |
| 7 | Starter Relay | Relay |
| 8 | Solenoid Return | Ground |
| 9 | Operator Seat Belt Warning Relay | Relay |
| 10 | Machine Lockout Lamp Relay | Relay |
| 12 | Starter Lockout Lamp Relay | Relay |
| 13 | Backup Alarm Relay | Relay |
| 15 | Hoist Lever Position Sensor | Pulse Width Modulated (PWM - Rotary) |
| 16 | Body Position Sensor | Pulse Width Modulated (PWM - Rotary) |
| 17 | Ambient Air Temperature Sensor | Pulse Width Modulated (PWM) Sensor |
| 19 | Requested Gear Command | Data Link to Transmission ECM |
| 21 | Backlight Intensity Control | Lamp Control |
| 22 | Ground | Ground |
| 23 | Differential (Axle) Oil Level Switch | (Not Used) |
| 24 | Steering Oil Temperature Sensor | Pulse Width Modulated (PWM) Sensor |
| 27 | Steering Tank Oil Level Switch | (Not Used) |
| 28 | Auto Lube Grease Sensor (Wiggins) | Limit Switch |
| 29 | Transmission/Torque Converter Oil Level Sensor (Wiggins) | Analog Active Sensor |
| 31 | Engine Coolant Level Sensor (Wiggins) | Analog Active Sensor |
| 35 | Shift Lever Position Sensor | Pulse Width Modulated (PWM) Sensor |
| 36 | SCAC Water Level/Urea Sensor (Wiggins) | Analog Active Sensor |
| 37 | Engine Oil Level Sensor (Wiggins) | Analog Active Sensor |
| 40 | Steering Accumulator Oil Pressure Sensor #2 | Pulse Width Modulated (PWM) Sensor |
| 41 | Steering Accumulator Oil Pressure Sensor #1 | Pulse Width Modulated (PWM) Sensor |
| 42 | Steering Pump Oil Pressure Sensor | Pulse Width Modulated (PWM) Sensor |
| 46 | Backlight Adjust Decrement Switch | Lamp Control |
| 47 | Starter Lockout Switch | Operator Controlled Switch |
| 48 | Fuel Level Sensor | Pulse Width Modulated (PWM) Sensor (Open Collector) |
| 51 | Auto Lube Pressure Sensor | (Not Used) |
| 53 | Hydraulic Hoist Screen Filter Bypass Switch | Pressure Actuated (Switch-to-Ground) |
| 56 | Global CAN A + (Redundant Pin) | CAN A Data Link + |
| 57 | Global CAN A Shield (Redundant Pin) | Shield |
| 59 | Machine Lockout | Operator Controlled Switch |
| 60 | Backlight Dimmer Switch | Lamp Control |
| 61 | Switch-To-Ground Input | Adaptive Economy Mode Switch |
| 62 | Access Ladder Monitoring: Pass | Proximity Switch |
| 63 | Ground | Ground |
| 64 | Local CAN B (+) | CAN Data Link (+) |
| 65 | Local CAN B (-) | CAN Data Link (-) |
| 66 | Local CAN B Shield | Shield |
| 67 | Global CAN A + (Main) | CAN A Data Link + |
| 68 | Global CAN A - (Main) | CAN A Data Link - |
| 69 | Global CAN A Shield (Main) | Shield |
| 70 | Global CAN A - (Redundant Pin) | CAN A Data Link - |
| (1) | The ECM responds to an active input only when all the necessary conditions are satisfied. |
| (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.
Transmission Input Speed Sensor
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| Illustration 5 | g03319060 |
The ECM receives signals from the "Transmission Input Speed Sensor" as a frequency signal. The "Transmission Input Speed Sensor" is an active sensor. The signal indicates the rotational speed of the connection from the output of the torque converter to the input of the transmission. The signal is generated by a gear passing in front of the sensor, with one full pulse generated per tooth on the gear. The signal is low when a gear tooth is in front of the sensor and high when between teeth.
Transmission Intermediate Speed
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| Illustration 6 | g03319339 |
The ECM receives signals from the "Transmission Intermediate Speed Sensor" as a frequency signal. The "Transmission Intermediate Speed Sensor" is a passive sensor. The signal indicates the rotational speed of the connection from the output of the first set of clutches (one, two, and three) in the transmission and the second set of clutches (four, five, and six). The signal is generated by a gear passing in front of the sensor, with one full pulse generated per tooth on the gear. The sensor has an inductive coil that creates a voltage pulse to the ECM when a gear tooth passes the sensor. The ECM interprets the frequency of the pulses as the speed of the gear.
Transmission Output Speed Sensors
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| Illustration 7 | g03319385 |
The ECM receives signals from the "Transmission Output Speed Sensors" as frequency signals. The "Transmission Output Speed Sensors" are passive sensors. The signals indicate the rotational speed of the output of the transmission. The signal is generated by a gear passing in front of the sensor, with one full pulse generated per tooth on the gear. The sensor has an inductive coil that creates a voltage pulse to the ECM when a gear tooth passes the sensor. The ECM interprets the frequency of the pulses as the speed of the gear.
Transmission Oil Temperature Sensor
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| Illustration 8 | g03319963 |
The "Transmission Oil Temperature Sensor" is an active pulse width modulated sensor. The sensor changes the duty cycle as the temperature changes. A lower duty cycle represents a lower temperature and a higher duty cycle represents a higher temperature. The ECM interprets the duty cycle and is able to determine the temperature of the transmission oil.
Torque Converter Oil Temperature Sensor
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| Illustration 9 | g03319963 |
The "Torque Converter Oil Temperature Sensor" is an active pulse width modulated sensor. The sensor changes the duty cycle as the temperature changes. A lower duty cycle represents a lower temperature and a higher duty cycle represents a higher temperature. The ECM interprets the duty cycle and is able to determine the temperature of the torque converter oil.
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| Illustration 10 | g06187624 |
The shift control lever is used to select forward speeds, neutral position, parking brake applied position, and reverse direction. To unlock and move the shift control lever, depress the top button on the left side of the shift handle.
The lower left button, along with a button (not shown) on the front of the lever, is used to test the parking brake.
The shift lever sensor is a pulse width modulated position sensor. The sensor sends a pulse width modulated signal to the ECM that corresponds to a specific position on the shift lever. Refer to Table 5. The ECM interprets the specific duty cycles as an operator request to be in a specific driving mode.
| Position | Duty Cycle |
| "P" | 10 ± 2% |
| "R" | 20 ± 4% |
| "N" | 44 ± 4% |
| "D" | 68 ± 4% |
| "2" | 84 ± 3% |
| "1" | 90 ± 2% |
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| Illustration 11 | g06187630 |
The "Drive Gear Select Increment Switch" is a momentary, single-pole switch. The drive gear select increment contact floats to a high voltage when the switch is not depressed, and is pulled low when the switch is depressed. The switch completes the circuit between the drive gear select increment contact and the return contact. The switch increases the maximum gear the transmission will engage when in the DRIVE position.
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| Illustration 12 | g06187634 |
The "Drive Gear Select Decrement Switch" is a momentary, single-pole switch. The drive gear select decrement contact floats to a high voltage when the switch is not depressed, and is pulled low when the switch is depressed. The switch completes the circuit between the drive gear select decrement contact and the return contact. The switch decreases the maximum gear the transmission will engage when in the DRIVE position.
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.
The "Auto Retarder Control (ARC)" On/off, "ARC" Up/down, and "Throttle Backup" switches are located below the "Information Panel" display. The "Information Panel" display is located above the center console.
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| Illustration 13 | g06191775 |
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ARC On/Off switch | |
The "Auto Retarder Control (ARC)" on/off switch activates the ARC feature. Pressing the top of the switch turns on the ARC. Pressing the bottom of the switch turns off the ARC.
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| Illustration 14 | g06191757 |
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ARC Up/down switch | |
When the ARC function is on, the ARC up/down switch is used to set the proper machine speed. Pressing the top or the bottom of the switch for 3 seconds will set the desired ground speed. To increase the speed while in ARC mode, momentarily press the top of the switch. To decrease the speed of the truck in ARC mode, momentarily press the bottom of the switch.
The "Throttle Backup" switch (not shown) is used of the throttle position sensor on the accelerator does not function. The switch is used to raise the engine rpm above low idle, allowing the operator to transport the truck to a service area.
Transmission Charge Filter Bypass Switch
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| Illustration 15 | g03320660 |
The "Transmission Charge Filter Bypass Switch" is a pressure switch. The switch alerts the ECM when the "Transmission 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.
Differential Oil Level Switches
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| Illustration 16 | g03330567 |
The "Differential Oil Level Switches" are fluid detection switches. The switch sends a signal showing either the presence or lack of differential oil at a certain level in the system. The switch has a seven second anti-slosh feature, and is used to alert the ECM that differential oil is low.
Torque Converter Oil Level Switch (if equipped)
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| Illustration 17 | g03330567 |
The "Torque Converter Oil Level Switch" (if equipped) is a fluid detection switch. The switch sends a signal showing either the presence or lack of transmission oil at a certain level in the system. The switch has a seven second anti-slosh feature, and is used to alert the ECM that torque converter oil is low.
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 18 | g03319894 |
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ECPC Solenoid 1-6 ECPC Lockup Clutch Solenoid | |
Each of these solenoid valves is designed to control the flow of hydraulic oil to a clutch plate. When the solenoid is not engaged or receiving a low duty cycle signal, the solenoid does not allow power train hydraulic oil to engage a clutch plate. As the duty cycle of the signal to the solenoid increases, the solenoid allows some flow and the clutch begins to engage. When the duty cycle of the signal to the solenoid is at the maximum, the flow of power train hydraulic oil fully engages the clutch. The engagement of a clutch is proportional to the duty cycle of the signal sent by the ECM.
Note: The solenoid coils are not designed to operate using 24 VDC directly. The ECM sends a PWM signal of 24 VDC at a duty cycle that will provide the necessary current to the solenoid coils. Do NOT activate the coils by using 24 VDC (+battery). The life of the coils will be reduced drastically. A source of 12 VDC should be used, if the coils must be activated by not using the ECM.
Electronic communication between the "Machine Control ECM", the "Implement Control 2 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 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. Cat D® 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 Cat® 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 to communicate with Cat® 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 Cat® ET to change the operating modes. Cat® ET will read the service codes that are stored in the memory of the ECM. 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 Cat® 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 39.
A data link is required for communication with 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.