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| Illustration 1 | g00813808 |
View of the Right Rear Side of the Cab Power Train Electronic Control Module (ECM) | |
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| Illustration 2 | g00291779 |
Power Train Electronic Control Module (1) J1 connector. (2) J2 connector. | |
The electronic control module (ECM) for the power train is located inside the cab at the right rear side. The power train ECM is installed behind a cover panel.
The power train ECM electronically controls the shifting of the transmission. The power train ECM responds to the requests of the operator by activating the appropriate solenoid valves. The solenoid valves direct oil to the corresponding transmission clutches.
The power train ECM also operates in the automatic shift mode. In the automatic mode, the power train ECM activates the appropriate solenoid valves, depending on the switch settings and the transmission output speed. The power train ECM also controls the following functions: neutral start, deceleration and backup alarm.
The power train electronic control module (ECM) makes decisions based on input information and memory information. The corresponding response is made through the outputs. The inputs and the outputs of the ECM are joined to the harness by two 40 contact connectors.
Inputs
Numerous inputs inform the ECM of the status of the machine conditions. The two types of inputs are switch inputs and sensor inputs. Switches provide an open, a ground, or a +battery signal to the switch inputs of the ECM. Sensors provide a constantly changing signal to the sensor inputs of the ECM. The inputs are listed in the Tables that follow.
Outputs
The ECM responds to decisions by sending electrical signals through the various outputs. The outputs create an action or the outputs provide information. The outputs are listed in Tables that follow.
Input/Output
The CAT data link is used to communicate with other electronic control modules on the machine. The data link is bidirectional. The ECM can send information and the ECM can receive information. The data link allows the sharing of information with other electronic control modules.
An example of data link communication would be engine speed information that is sent by the power train ECM to the implement ECM. The ECM also exchanges diagnostic information with the Caterpillar Monitoring System.
A module identifier (MID) is assigned to all electronic control modules that use the data link. The MID for the power train ECM is 081.
| Machine Codes | |
| Sales Model (PIN) | Machine Code |
| 824G | 47 |
| 825G | 48 |
| 826G | 49 |
| 40-Pin Connector J1 | ||
|---|---|---|
| No. (1) | Function | Type |
| 1 | + Battery | Power |
| 2 | Ground | Ground |
| 3 | Cat Data Link - | Input/Output |
| 5 | Ground | Ground |
| 6 | + Battery | Power |
| 7 | Solenoid Return | Output Return |
| 8 | Start Relay | Solenoid Output |
| 9 | CAT Data Link + | Input/Output |
| 11 | Forward Solenoid | Solenoid Output (ON/OFF) |
| 13 | Neutral Switch | Switch Input (open/ground) |
| 14 | Reverse Direction Switch | Switch Input (open/ground) |
| 15 | Switch and Sensor Return | Sensor Input |
| 16 | Switch and Sensor Return | Sensor Input |
| 17 | Reverse Solenoid | Solenoid Output (ON/OFF) |
| 19 | Upshift Switch (N.C.) | Switch Input (open/ground) |
| 20 | VCS #1 (Minimum) | Switch Input (open/ground) |
| 21 | Deceleration Enable | Switch Input (open/ground) |
| 22 | Deceleration Enable | Switch Input (open/ground) |
| 23 | Upshift Switch (N.O.) | Switch Input (open/ground) |
| 24 | VCS #2 (Mid 1) | Switch Input (open/ground) |
| 25 | Downshift Switch (N.C.) | Switch Input (open/ground) |
| 26 | Downshift Switch (N.O.) | Switch Input (open/ground) |
| 27 | Parking Brake Switch (N.C.) | Switch Input (open/ground) |
| 29 | Auto/Man Switch (Manual) | Switch Input (open/ground) |
| 30 | Forward Switch to Ground | Switch Input (open/ground) |
| 31 | Auto/Man Switch (Auto 4) | Switch Input (open/ground) |
| 32 | Auto/Man Switch (Auto 3) | Switch Input (open/ground) |
| 33 | Auto/Man Switch (Auto 2) | Switch Input (open/ground) |
| 35 | VCS #3 (Mid 2) | Switch Input (open/ground) |
| 36 | Park Brake Switch (N.O.) | Switch Input (open/ground) |
| 39 | VCS #4 (Maximum) | Switch Input (open/ground) |
| 40 | Start Switch Key | Switch Input (open/(+) battery) |
| ( 1 ) | The connector contacts that are not listed are not used. |
| 40-Pin Connector J2 | ||
|---|---|---|
| No. (1) | Function | Type |
| 1 | Speed 3 Solenoid (2) | Solenoid Output (ON/OFF) |
| 2 | Speed 1 Solenoid | Solenoid Output (ON/OFF) |
| 3 | Solenoid Return | Output Return |
| 4 | Left Pedal Position Sensor | Frequency Input |
| 6 | Primary Steering Pressure Switch (N.C.) | Switch Input (open/ground) |
| 7 | Speed 4 Solenoid (2) | Solenoid Output (ON/OFF) |
| 8 | Speed 2 Solenoid | Solenoid Output (ON/OFF) |
| 10 | Primary Steering Pressure Switch (N.O.) | Switch Input (open/ground) |
| 12 | Sensor Power Supply (8 V) | Sensor Supply (+8 V) |
| 14 | Transmission Speed Sensor | Frequency Input |
| 18 | Transmission Oil Temperature | Pulse Width Modulated |
| 20 | Transmission Speed Sensor Return | Frequency Input |
| 23 | Transmission Input Speed Sensor - | Frequency Input |
| 25 | Transmission Output Speed Trailing + | Frequency Input |
| 29 | Transmission Input Speed Sensor + | Frequency Input |
| 31 | Transmission Output Speed Trailing - | Frequency Input |
| 37 | Backup Alarm | Solenoid Output (ON/OFF) |
| 38 | Engine Speed | Frequency Input |
| ( 1 ) | The connector contacts that are not listed are not used. |
| ( 2 ) | Only on three and four speed machines. |