The automatic shift switch that is located in the cab allows the operator to enable the automatic shift function or the automatic shift switch allows the operator to disable the automatic shift function. When the automatic shift function is engaged, the lamp (automatic shift) will illuminate.
When the automatic shift function is enabled the operator may place the shift lever in any position higher than third gear ("4F" through "8F" or "4R" through "6R") and the power train ECM will automatically shift the transmission through the proper gears. This depends on the speed of the machine and the operating conditions.
Note: The gears "1F" through "3F" are selected manually with the shift lever. The gears "1R" through "3R" are manually selected with the shift lever.
The position of the clutch pedal is determined by a pulse width modulated sensor. The output of the sensor is used by the power train ECM in order to control the hydraulic pressure of the direction clutches.
During a failure of the position sensor (clutch pedal), the limit switch (clutch pedal) controls the pressure that is applied to the direction clutches. The limit switch (clutch pedal) allows the machine to operate at a reduced level.
This function restricts starting of the engine if the shift lever is not in the NEUTRAL position or the PARK position. When the shift lever is in the NEUTRAL position or the PARK position the power train ECM energizes the coil of the starter relay. This energizes the starting motor solenoid.
The power train ECM monitors the speed of the machine. When the ECM detects an overspeed condition the ECM will upshift the transmission in order to relieve the overspeed condition. Upshifts may occur through high gear.
The speed of the machine may be limited by disabling the engagement of the "8th" gear. Speed limiting is accomplished via manual selection or the automatic shift function. This will reduce the maximum attainable speed.
The backup alarm is used in order to alert personnel that the machine is backing up. When the operator places the transmission into the REVERSE position, the ECM activates the backup alarm and the alarm sounds.
The power train ECM utilizes information from the transmission output speed sensors in order to calculate the direction and ground speed of the machine. The ground speed information and the direction information is sent to the Caterpillar Monitoring System via the CAT data link.