TM 5-3805-290-23-1
THEORY OF OPERATION - CONTINUED
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TRANSMISSION - CONTINUED
a.
Switches.
General. Switches provide information to ECM. Switches are two-state devices, meaning they are either
(1)
open or closed.
(a) Closed - Switch closes circuit to ground or switch closes circuit to battery.
(b) Open - Switch opens a circuit to ECM input.
Engine Start Switch.
(2)
(a) When engine start switch is in ON position, electrical power from batteries is supplied to ECMs.
(b) When engine start switch is in START position and conditions for starting engine are satisfied, start
relay is energized.
Downshift Switch. Downshift switch tells ECM that operator wants transmission to downshift one gear.
(3)
Downshift switch has one input connection to ECM.
Autoshift Switch.
(4)
(a) Autoshift switch tells ECM mode that is selected by operator.
(b) Autoshift switch has one input connection to ECM.
(c) When operator selects AUTO mode, ECM will select proper transmission gear.
(d) Proper transmission gear is based upon transmission speed.
(e) Machine must be in NEUTRAL to activate AUTO mode.
(f) When operator selects MANUAL mode, transmission gear selection is made by operator.
(g) Operator uses transmission direction and shift lever to select transmission gear.
(h) When operator selects ECONOMY mode, ECM will select transmission gear but transmission will
shift at lower transmission speeds.
(i) Machine ECM will use these inputs in order to engage proper clutches:
Transmission shift lever
Intermediate speed sensors
Output speed sensors
Torque converter output speed sensor
Transmission neutralizer override switch
Autoshift switch
Downshift switch
Remote F/N/R switch
Brake charging pressure sensor
Parking brake switch
Engine ECM
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