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 transmission ECM processes information based 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 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.
| Implement ECM Connector J1 Contact Descriptions (1) | ||
|---|---|---|
| No. | Type | Function |
| 1 | Key Switch Input | Key ON |
| 10 | Cat Data Link (+) | Cat Data Link + |
| 11 | Sensor Power Output | 5V Power Supply |
| 13 | Battery Return | Battery - |
| 20 | Cat Data Link (-) | Cat Data Link - |
| 21 | Sensor Power Return | 5V Return |
| 23 | Battery Return | Battery - |
| 39 | Batter Power Input | Battery + |
| 44 | Sensor Power Output | 8V Power Supply |
| 45 | Sensor Power Return | 8V Return |
| 47 | Battery Power Input | Battery + |
| 56 | Sensor Power Return | 10V Return |
| 57 | Battery Return | Battery - |
| 70 | Battery Return | Battery - |
| (1) | Contacts that are not listed are not used. |
| Implement ECM Connector J2 Contact Descriptions (1) | ||
|---|---|---|
| No. | Type | Function |
| 7 | Sourcing Drive Output | Back Up Alarm |
| 8 | Sourcing Drive Return | Driver Return |
| 67 | CAN Data Link (+) | CAN A+ |
| 68 | CAN Data Link (-) | CAN A- |
| (1) | Contacts that are not listed are not used. |
| Power train ECM Connector J1 Contact Descriptions (1) | ||
|---|---|---|
| No. | Type | Function |
| 1 | Key Switch Input | Key ON |
| 2 | Differential Speed Input (+) | TC Output SP / Transmission Input SP + |
| 3 | Differential Speed Input (-) or Hall Effect Input | TC Output SP / Transmission Input SP - |
| 4 | Differential Speed Input (+) | Transmission INTMD SP / Planetary Member SP + |
| 5 | Differential Speed Input (-) or Hall Effect Input | Transmission INTMD SP / Planetary Member SP - |
| 6 | Differential Speed Input (+) | Transmission Output Speed Sensor 1+ |
| 7 | Differential Speed Input (-) or Hall Effect Input | Transmission Output Speed Sensor 1 - |
| 8 | Differential Speed Input (+) | Transmission Output Speed Sensor 2+ |
| 9 | Differential Speed Input (-) or Hall Effect Input | Transmission Output Speed Sensor 2 - |
| 10 | Cat Data Link (+) or CAN Data Link (-) | Cat Data Link + |
| 11 | Sensor Power Output | 5 V Power Supply |
| 12 | Sourcing Driver Output | Transmission Bypass / LO R HI F Synchro V |
| 13 | Battery Return | Battery - |
| 16 | Differential Speed Input (-) or Hall Effect Input | Front Axle Speed - |
| 18 | Differential Speed Input (-) or Hall Effect Input | Rear Axle Speed - |
| 20 | Cat Data Link (-) or CAN Data Link (+) | Cat Data Link - |
| 21 | Sensor Power Return | 5V Return |
| 22 | Analog Input | Transmission Oil Temperature Sensor |
| 23 | Battery Return | Battery - |
| 27 | Switch to Ground Input | Identification Code 2 |
| 29 | Analog Input | Torque Converter / Variator Flushing Oil Temperature |
| 30 | Analog Input | Front Axle Oil Temperature Sensor |
| 31 | Battery Power to Input | Battery + |
| 32 | Switch to Ground Input | Identification Code Enable |
| 33 | Switch to Ground Input | Forward Direction Switch |
| 34 | Switch to Ground Input | Neutral Direction Switch |
| 35 | Switch to Ground Input | Reverse Direction Switch |
| 36 | Analog Input | Park Brake Pressure Sensor |
| 37 | Analog Input | Brake Accumulator Oil Pressure Sensor |
| 39 | Battery Power Input | Battery + |
| 40 | Switch to Ground Input | First Speed Shift |
| 41 | Switch to Ground Input | Armrest Position Switch N/C |
| 42 | Switch to Ground Input | Armrest Position Switch N/O |
| 43 | Switch to Ground Input | Second Speed Shift |
| 44 | Sensor Power Output | 8V Power Supply |
| 45 | Sensor Power Return | 8V Return |
| 47 | Battery Power Input | Battery + |
| 48 | Sourcing Driver Output | Clutch 6 / PPV Pump Control A |
| 49 | Sourcing Driver Output | Main Relief Pressure / PPV Pump Control B |
| 50 | Sourcing Driver Return | Driver Return |
| 51 | Sourcing Driver Output | Lockup Clutch / Low F High R Synchronizer Valve |
| 52 | Clutch one Forward/ Low R High F Synchronizer Valve | |
| 53 | Analog Input | Axle Oil Temperature Sensor |
| 54 | Sourcing Driver Output | Driver Return |
| 55 | Sourcing Driver Return | Driver Return |
| 56 | Sensor Power Return | 10V Return |
| 57 | Battery Return | Battery - |
| 58 | Sourcing Driver Output | Clutch three Forward / Auxiliary Synchronizer Valve |
| 59 | Sourcing Driver Output | Clutch five / Synchronizer Fork Pressure Supply |
| 60 | Sourcing Driver Return | Driver Return |
| 61 | Sourcing Driver Output | Differential Lock (Rear) |
| 62 | Sourcing Driver Output | Differential Lock (Front) |
| 63 | Switch to Ground Input | Third Speed Shift |
| 64 | Switch to Ground Input | Transmission Oil Filter Bypass Switch |
| 65 | Sourcing Driver Output | Clutch four / A |
| 66 | Sourcing Driver Output | Clutch two (FWD)/B |
| 69 | Sensor Power Output / Sourcing Driver Output | 10 V Power Supply |
| 70 | Driver Return | Battery - |
| (1) | Contacts that are not listed are not used. |
| Power train ECM Connector J2 Contact Descriptions (1) | ||
|---|---|---|
| No. | Type | Function |
| 7 | Sourcing Driver Output | Start Relay |
| 8 | Sourcing Driver Return | Driver Return |
| 9 | Sinking Driver Output | Axle Oil Cooler Clutch |
| 23 | Switch to Ground Input | Transmission Oil Filter Bypass 2 |
| 36 | Switch to Ground Input | D Speed Shift |
| 38 | Switch to Ground Input | Manual Differential Lock N/O |
| 40 | PWM Input | Speed Range Thumbroller |
| 42 | PWM Input | Direction Switch |
| 43 | PWM Input or Analog Input | Direction Switch Redundant |
| 44 | Switch to Ground Input | Transmission Downshift / Throttle Lock Set N/O |
| 67 | CAN Data Link (+) | CAN A + |
| 68 | CAN Data Link (-) | CAN A - |
| (1) | Contacts that are not listed are not used. |
The inputs describe the status of the machine systems. Two types of inputs exist. The inputs can be either a switch type or a sensor type. Switches provide an open, a ground, or a + battery signal to the inputs of the controller. Sensors (frequency, PWM, or voltage) provide a changing signal to the sensor inputs of the controller. The inputs to ECMs are listed in Tables 3 and 3.
Transmission Oil Temperature Sensor
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| Illustration 2 | g02108634 |
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Transmission Oil Temperature Sensor | |
The transmission oil temperature sensor is a two-wire passive temperature sensor that is located on the transmission oil pump inlet housing. The sensor is an input to the Power Train ECM. The oil temperature sensor information is used to adjust transmission clutch fill times.
The sensor sends an analog signal to the power train ECM indicating torque converter oil temperature. The resistance range for this sensor is 33,650 ohms at
Torque Converter Oil Temperature Sensor
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| Illustration 3 | g02108634 |
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Torque Converter Oil Temperature Sensor | |
The transmission oil temperature sensor is a two-wire passive temperature sensor that is located on the transmission oil cooler inlet fitting. The torque converter oil temperature information is sent by the Power Train ECM to the monitoring system. The torque converter temperature is displayed on the temperature gauge on the front dash panel.
The sensor sends an analog signal to the power train ECM indicating torque converter oil temperature. The resistance range for this sensor is 33,650 ohms at
Transmission Input Speed (Torque Converter)
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| Illustration 4 | g01445489 |
A passive two-wire magnetic frequency-type sensor converts mechanical motion to an AC voltage. The torque converter speed sensor measures torque converter output speed in the range of 25 to 3000 rpm. The speed sensor information is also used by the Power Train ECM to set and adjust transmission shift points.
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| Illustration 5 | g01445492 |
A passive two-wire magnetic frequency-type sensor converts mechanical motion to an AC voltage. The torque converter output speed sensor measures torque converter output speed in the range of 25 to 3000 rpm. The speed sensor information is also used by the Power Train ECM to set and adjust transmission shift points. Transmission speed sensors may be used in pairs.
Torque Converter Pedal Position Sensor
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| Illustration 6 | g01445493 |
The pedal position sensor determines the position of the torque converter pedal. The sensor sends a PWM signal to the ECM. The ECM monitors the signal. Then, the ECM calculates the position of the pedal from the signal. Information about the transmission output speed is broadcast on the Cat data link.
Transmission Oil Filter Bypass Switch
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| Illustration 7 | g03015918 |
The bypass switch is a pressure switch that shows whether the filter is plugged and the filter is being bypassed. This switch is normally open. When electrical power is applied to the switch, the switch closes. When the filter becomes plugged, the pressure of the oil opens the switch which allows the oil to bypass the filter.
This switch is one of the inputs that is used in order to drive the "system indicator" in the instrument cluster. This indicator is turned ON when the "Transmission oil filter bypass" switch is in the closed position and the transmission oil temperature is greater than
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| Illustration 8 | g03003739 |
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Key Start Switch | |
The key start switch is an input of the transmission electronic control module (ECM). The key start switch informs the transmission ECM of an attempt to start the engine. The transmission ECM then initiates the neutral start function.
During normal machine operation, the start terminal of the key start switch is open. When the key start switch is turned to the START position, the start terminal closes to the +battery. The +battery voltage is present at connector contact J2-1 of the transmission ECM. When all starting conditions are satisfied, the transmission ECM sends a +battery signal to the connector contact J2-7. The connector contact J2-7 is for the start relay that engages the starter for engine cranking.
Note: When the key start switch is in the ON position, a +battery signal is sent to connector contact J1-1. With +battery signal to connector contact J1-1 will activate the transmission ECM.
Note: After the key start switch is initially turned to the START position, the switch will not return to the START position from the ON position. The switch must be turned to the OFF position first. Then, the switch can be turned to the START position.
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| Illustration 9 | g03591717 |
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(1) Maximum Output (Downshift)
(2) Nominal Output (3) Minimum Output (Upshift) (4) Reverse (5) Neutral (6) Forward | |
Rotate the thumb wheel switch upward in order to signal the ECM to upshift the transmission one gear.
Rotate the thumb wheel switch downward in order to signal the ECM to downshift the transmission one gear.
| Thumb Wheel Switch Status | ||
|---|---|---|
| Position | ||
| Thumb Wheel Rotated Upward (3) | Minimal Output (Upshift) | Minimal PWM Output 20%+-3% |
| Released Thumb Wheel (2) | Nominal Output | Nominal PWM Output 50%+-3% |
| Thumb Wheel Rotated Downward (1) | Maximum Output (Downshift) | Maximum PWM Output 80%+-3% |
The direction switch has three positions: forward (6), neutral (5) and reverse (4). The operator selects the direction of the transmission through the switch.
| Switch Status | |||
|---|---|---|---|
| Position | Reverse (4) | Neutral (5) | Forward (6) |
| Reverse (4) | Closed | Open | Open |
| Neutral (5) | Open | Closed | Open |
| Forward (6) | Open | Open | Closed |
| Signal 1 and 2 PWM Output | |
|---|---|
| Position | |
| Reverse (4) | 9% - 20% Duty Cycle |
| Neutral (5) | 42% - 58% Duty Cycle |
| Forward (6) | 80% - 91% Duty Cycle |
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. The outputs of the ECM are listed in Tables 3 and 3.
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| Illustration 10 | g01237747 |
The solenoids engage the speed clutches and direction clutches in the transmission.
Note: Do not apply direct battery voltage to the solenoids. The solenoids are not designed for operating with 24 VDC.
Torque Converter Lockup Clutch Solenoid
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| Illustration 11 | g01444286 |
The solenoid functions as a proportional valve. The solenoid modulates hydraulic pressure to the lockup clutch. The ECM increases the PWM Driver to the solenoid valve and the hydraulic pressure at the lockup clutch is increased. The ECM decreases the PWM Driver to the solenoid valve and the hydraulic pressure at the lockup clutch is at a minimum.
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 Transmission Electronic Control Module is 081.
A data link is required for communication with the service tool (Cat ET) and the electronic control modules. A data link is also required for instrument clusters and other devices that use service tool (Cat ET) communications protocol. The data link is not used in order to broadcast any diagnostic information.