LINES GP-FUEL INJECTION 1068273 - Caterpillar

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.STIC Control
Illustration 9 g03591717
(1) Maximum Output (Downshift)
(2) Nominal Output
(3) Minimum Output (Upshift)
(4) Reverse
(5) Neutral
(6) Forward Upshift
Rotate the thumb wheel switch upward in order to signal the ECM to upshift the transmission one gear.Downshift
Rotate the thumb wheel switch downward in order to signal the ECM to downshift the transmission one gear.
Table 5
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% Direction
The direction switch has three positions: forward (6), neutral (5) and reverse (4). The operator selects the direction of the transmission through the switch.
Table 6
Switch Status
Position Reverse (4) Neutral (5) Forward (6)
Reverse (4) Closed Open Open
Neutral (5) Open Closed Open
Forward (6) Open Open Closed
Table 7
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 Outputs
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.Solenoids
Transmission Clutch Solenoids
Illustration 10 g01237747The 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 (If Equipped)
Illustration 11 g01444286The 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.Data Link
Cat Data Link
The Cat Data Link is an input/output of the ECM. The data