ELECTRICAL
4203781 First Edition 4-45
4
Cruise Control—Theory of Operation
Unswitched Power Circuit
Unswitched power is available from the battery positive
terminal to the starter motor battery terminal and then
from the starter motor battery terminal to 50-amp circuit
breaker (F1) battery terminal. Unswitched power is
available through the 50-amp circuit breaker (F1) to
30-amp circuit breaker (F2) input terminal and from
circuit breaker (F2) input terminal to 10-amp circuit
breaker (F5).
Unswitched power is available from 30-amp circuit
breaker (F2) output terminal to accessory relay terminal
30.
Unswitched power is provided from 10-amp circuit
breaker (F5) to PTO switch terminal E and then from
terminal E to time delay relay +12V terminal.
Switched Power Circuit
When the key switch is turned to the run position, voltage
is provided from key switch terminal I to accessory relay
terminal 86, energizing the relay. With the relay
energized, switched power is provided from accessory
relay terminal 87 to PTO switch terminal B and from
terminal B to the seat switch.
Accessory relay terminal 87 also provides switched
power to 10-amp circuit breaker (F6). Circuit breaker (F6)
provides voltage to horn relay terminal 30 and from horn
relay terminal 86 to the brake pedal switch.
Interlock Circuit
The operator must be on the seat before releasing the
park brake. (See “Run Circuit—Theory of Operation” on
page 4-30.)
Cruise Control Circuit
When the brake pedal switch is in the on position, voltage
is provided to the cruise control switch and then to cruise
control relay terminal 30.
When the cruise control switch is momentarily placed in
the enable position, voltage is provided to cruise relay
terminal 86, energizing the relay. With the relay
energized, voltage is provided from cruise relay terminal
87 to the cruise control magnet, activating the magnet. At
the same time voltage is also provided from cruise relay
terminal 87 to cruise cancel relay terminal 87A. Now the
cruise cancel relay terminal 30 provides voltage back to
the cruise control switch, and then to cruise relay terminal
86, keeping the relay energized.
The cruise relay will continue to activate the cruise
control magnet until the following occurs:
• Brake pedal is depressed, placing the brake pedal
switch in the off position.
• Cruise control switch is momentarily placed in the
disable position.
When the cruise control switch is placed in the disable
position, voltage is provided to cruise cancel relay
terminal 86, energizing the relay. With the cruise cancel
relay energized, voltage is interrupted to the cruise
control switch and to cruise relay terminal 86,
de-energizing the relay. With the cruise relay
de-energized, the cruise control circuit is turned off.
Diode (V8) conducts to ground the reverse voltage
generated when the cruise control magnet de-activates.
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