ELECTRICAL
4181383 First Edition 4-27
4
Run Circuit—Theory of Operation
Power Circuit
Unswitched power is available from the battery positive
terminal to the starting motor battery terminal and then
from the starting motor battery terminal to 50 amp
thermal circuit breaker battery terminal.
Unswitched power is available from 50 amp thermal
circuit breaker battery terminal to key switch terminal A
and control module terminal J3-6.
When the key switch is turned to the run position, voltage
is provided from key switch terminal B to control module
switch power input terminal J3-2, powering up the control
module and energizing the internal switched power relay.
Voltage is also provided from key switch terminal B to
control module select 2 input terminal J4-2, activating the
input. With the select 2 input activated, the control
module selects the software program for this machine.
This allows the control module to be used in more than
one machine.
With the internal switched power relay energized,
switched power is available from switched power relay
terminal 87 to control module terminal J3-5. Switched
power is available from control module terminal J3-5 to
splice 100.
From splice 100, switched power is available to the park
brake and neutral proximity switches.
With the key switch in the run position, the control module
performs a control panel lamp check for approximately 4
seconds. At the same time the control module performs a
horn test. During the test the horn will chirp six times.
Run Circuit–On Seat
When the operator is on the seat, the seat switch
contacts close. With the seat switch contacts closed,
voltage is provided to control module seat switch input
terminal J1-8, activating the input. With the input
activated, the control module allows the engine to
continue to operate when the park brake is released.
With the seat switch input activated, control module fuel
hold-in output terminal J2-7 continues to provide voltage
to the fuel shutoff hold-in coil, keeping the fuel shutoff
solenoid plunger retracted. With the solenoid plunger
retracted, fuel continues to flow to the engine. Voltage is
also provided from fuel hold output terminal to the fuel
pump and the pump continues to operate.
The control module will de-energize the fuel shutoff
solenoid if the following should occur:
• After initially starting the machine, and if the operator
should depress the traction pedal with the park brake
locked.
• If the operator should leave the seat with the park
brake in the released position.
The control module will de-energize the fuel shutoff
solenoid approximately 1 second after the seat switch
contacts open. The time delay is to compensate for seat
bounce when operating the machine over rough terrain.
When the operator stops moving the machine and locks
the park brake, the control module will sound the horn to
alert the operator that the park brake pedal is set when
the traction pedal is cycled. There is a 2 second delay
before the control module activates the horn.
Run Circuit–Off Seat
Before leaving the seat, the mow switch must be in the off
position and the following interlock switches must be
activated:
• Park brake proximity switch
• Neutral proximity switch
With the brake pedal in the locked position, the brake
pedal linkage is brought near the magnetic target zone of
the park brake proximity switch, activating the switch.
With the switch activated, voltage is provided from the
proximity switch to control module park brake switch input
terminal J1-7, activating the input.
With the traction pedal in the neutral position, the traction
pedal linkage is brought near the magnetic target zone of
the neutral proximity switch, activating the switch. With
the switch activated, voltage is provided from the
proximity switch to control module neutral switch input
terminal J1-2 activating the input.
Note: The proximity switch is a solid state switch and will
have approximately 2—3 voltage drop across the switch
when activated.
With the interlock switch inputs satisfied, control module
fuel hold output terminal J2-7 continues to provide
voltage to the fuel shutoff solenoid hold-in coil, allowing
the engine to continue to operate when the operator
leaves the seat. Voltage is also provided from fuel hold
output terminal to the fuel pump and the pump continues
to operate.
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