The interlock prevents the machine from accidental movement. The feature also prevents the operator from accidentally driving through the parking brake. The transmission will not shift to first gear forward or the transmission will not shift to first gear reverse when the parking brake is engaged. The ECM shifts the transmission to the NEUTRAL position when the transmission is in a gear and the parking brake is set. The transmission will not shift to a gear when the parking brake is released. The transmission must first be shifted to NEUTRAL in order to shift to a gear.
Driving through the Parking Brake
This feature provides the capability to shift to first gear when the parking brake is engaged. The parking brake is engaged and the plunger that is in the cab pops out if the pressure for releasing the parking brake is not available. The operator can drive through the parking brake for a short distance. Hold the parking brake switch that is located in the cab in the OFF position. The switch contains a spring in order to resist this effort. This switch will automatically move to the ON position when the switch is released. Move the direction switch in the forward position or the reverse position. Do not release the parking brake switch. The transmission will shift to the respective gear. See table1 for more information.
| State | STIC control | Parking Brake Switch | Parking Brake | Transmission Gear | Display |
|---|---|---|---|---|---|
| Initial | "1F" | OFF | OFF | "1F" | "1F" |
| Brake ON failure | "1F" | ON | ON | "1N" | "1N" |
| Direction to Neutral | "1F" | ON | ON | "1N" | "1N" |
| Switch in OFF | "1N" | OFF | ON | "1N" | "1N" |
| Direction to Forward or Reverse | "1F" or "1R" | OFF | ON | "1F" or "1R" | "1F" or "1R" |
| |
| Illustration 1 | g01478268 |
The operator uses the parking brake switch in order to set the brake. The ECM sets the brake if the operating conditions of the machine are appropriate. The ECM will log a diagnostic code of CID 0070 for the switch.
| Switch Status | ||
| Switch Position | Normally Open | Normally Closed |
| Out | Closed | Open |
| In | Open | Closed |
| |
| Illustration 2 | g01478277 |
The parking brake pressure switch provides the ECM with information about the hydraulic portion of the parking brake assembly. The parking brake is applied by a spring. The parking brake is released by hydraulic pressure. The parking brake is on when the pressure switch is not actuated. The parking brake is off when the pressure switch is actuated. The ECM will log a diagnostic code of CID 0627 for the switch.
| Switch Status | ||
| Switch Position | Normally Open | Normally Closed |
| High Pressure | Closed | Open |
| Low Pressure | Open | Closed |
Position of Torque Converter Pedal
| |
| Illustration 3 | g01478288 |
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. The ECM will log a diagnostic code of CID 1712 for the torque converter pedal position sensor.
Torque Converter Lockup Clutch Solenoid (Attachment)
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| Illustration 4 | g01478292 |
The solenoid functions as a proportional valve. The solenoid modulates hydraulic pressure to the lockup clutch. The ECM increases the current to the solenoid valve and the hydraulic pressure at the lockup clutch is increased. The ECM decreases the current to the solenoid valve and the hydraulic pressure at the lockup clutch is at a minimum. The ECM will log a diagnostic code of CID 0679 for the lockup clutch solenoid.