Shift Lever - The direction and speed switches are located in the shift lever console. These switches tell the ECM the requests of the operator: forward, reverse, neutral, first gear, second gear, third gear, fourth gear, fifth gear and sixth gear. The ECM responds to shifts by activating the appropriate transmission clutch solenoids.
Transmission Speed Sensor - This Allows the ECM to automatically shift to the appropriate gear.
Transmission Clutch Solenoids - These solenoid valves are located on the transmission. The valves direct pilot oil to the ends of the control spool. The control spool will shift allowing pressure oil to the corresponding clutches. The ECM activates the appropriate solenoid valves. The following solenoid valves are for direction: 1, 2 and 3. The following solenoid valves are for speed: 4, 5 and 6. In order to move the machine, two solenoid valves are activated. One solenoid is for direction and one solenoid is for speed. When the machine is in neutral only solenoid valve "4" is activated.
Lockup Clutch - The lockup clutch solenoid valve controls the lockup operation (direct drive).
Operation Of The Neutral Start Function
This function is enabled when the operator selects neutral at the shift lever, and the operator turns the key start switch to the START position. The shift lever switch tells the ECM that the shift lever is in neutral. The +battery signal from the key start switch tells the ECM that the key start switch is in the START position. This function allows an engine to start only when the shift lever is in neutral. When this function is enabled, the ECM activates the start relay that then cranks the starting motor. The following conditions are needed to start the engine:
- The shift lever must be in neutral.
- The parking brake must be engaged.
- The battery voltage must be less than 36 volts.
- The engine speed is 0 RPM.
- The key start switch is in the START position.
- The Prelubrication function is not active.
The start relay will automatically disengage if the engine is running over 300 RPM.
The ECM also performs a function that can prevent starting. This function is enabled when the electrical system voltage (+battery) is greater than 36 volts. The ECM internally monitors electrical system voltage (+battery) that is present at connector J1-1. This function protects the starting system during incorrect jump starting. The charging system is also protected. When this function is enabled, the ECM does not activate the start relay during the related neutral start function.
Directional Shift Management Function
The directional shift management function reduces stress on the driveline. This function is activated when the engine speed is greater than 1350 rpm and the operator shifts out of neutral or through neutral. The electronic engine control reduces the amount of fuel that is going to the engine. The subsequent reduction in power reduces stress on the driveline.
The prelubrication system uses an electric pump to lubricate the engine before starting. This action reduces engine wear.
An electronic engine control is used to energize the prelube pump. The transmission ECM sends a signal to the electronic engine control. The electronic engine control then activates the prelube system. A service tool is used to enable this feature. The desired state must be programmed into the electronic engine control.
When the operator turns the key start switch to the START position, the transmission ECM attempts prelube. The transmission ECM tells the engine control to prelube the engine. Status is sent from the electronic engine control, and the transmission ECM will not allow the machine to start until prelube is complete.
Note: In order to prelube the machine, the key start switch must be held in the CRANK position. If prelube is active, and the key start switch is moved out of the CRANK position, then the transmission ECM will command the electronic engine control to turn off the prelube. When the prelube is complete, the ECM will start the machine. There are two important rules when you are starting the engine:
- IF PRELUBE IS NEEDED, DO NOT START THE MACHINE .
- If the CAT Data Link fails and the prelube is ON, then the hardware can be damaged during an engine start.
- If the CAT Data Link fails and the prelube is ON, then the hardware can be damaged during an engine start.
- DO NOT DELAY STARTING THE MACHINE IF PRELUBE IS NOT NEEDED.
- The prelube is turned off at the electronic engine control.
- The engine control does not support prelube.
- There is a broken data link between the ECM and the engine control.
- The prelube is enabled, but conditions do not justify use.
- The prelube is turned off at the electronic engine control.
The parking brake function prevents the operator from operating the machine while the parking brake is engaged. Driving through the parking brake will cause accelerated wear to the friction components of the parking brake. The parking brake function of the ECM helps prevent driving through the parking brake by performing the following actions:
- The ECM may shift the transmission to NEUTRAL if the operator places the shift lever in FORWARD or REVERSE. The ECM will perform this shift if the parking brake is engaged with the transmission in speed 1.
- The ECM activates a warning category 1 or 3 on the Caterpillar Monitoring System by sending a signal over the CAT Data Link. Warning category 1 is activated whenever the parking brake is engaged. The parking brake indicator will FLASH. Warning category 3 is activated if the operator places the shift lever in FORWARD or REVERSE and the parking brake is engaged. The parking brake indicator will FLASH. The action lamp will FLASH and the action alarm will SOUND.
The backup alarm function alerts the surrounding personnel that the machine is backing up. Whenever the shift lever is in the REVERSE position, the ECM activates the backup alarm relay. The relay then activates the backup alarm.
When the operator depresses the neutralizer pedal, the transmission is neutralized.
If the machine is in neutral and the parking brake is engaged, then the machine will not be allowed to shift out of neutral. Partially depressing the neutralizer pedal forces the machine to converter drive. Depressing the neutralizer pedal more forces the machine to neutral. Depressing the brake pedal more forces the machine to neutral.
The gear and direction of the transmission is shown on Caterpillar Monitoring System. The ECM sends this information to Caterpillar Monitoring System on the data link.
The ECM controls the differential lock. The ECM reads the status of the differential switch, and the solenoid is driven. The differential is automatically unlocked when the machine is articulating.