Jacobsen AR3, Technical/Repair Manual

Page: 87 / 342

4-30 4181384 First Edition
ELECTRICAL
4
Start Circuit
With the start relay energized and when the key switch is
turned to the start position, current flows from key switch
terminal 50 to the starter motor solenoid, energizing the
solenoid. To energize the starter solenoid, current flows
from key switch terminal 50 to the following components:
• 15 amp fuse F6
• Start relay terminals 5 and 3
• Console connector X1, terminal 7
• Starter solenoid terminal
With the starter solenoid energized, current flows
between the starter solenoid contacts to the starter
motor, engaging the motor.
Diode module V1 conducts to ground the reverse voltage
generated when the starter solenoid is de-energized.
Current also flows from the start circuit to glow plug timer
terminal 4, activating the input. With the input activated
and terminal 6 grounded, the glow plug timer cancels,
lighting the glow plug wait light. Current also flows to the
glow plug circuit. (See “Glow Plug Circuit—Theory of
Operation” on page 4-26.)
With the key switch in the start position, current also
flows to the fuel shutoff solenoid pull-in coil, energizing
the coil. With the pull-in coil energized, the fuel shutoff
solenoid plunger retracts. The pull-in coil is a high-current
winding and is energized only when the key switch is in
the start position.
When the key switch is released to the run position, the
fuel shutoff solenoid hold-in coil keeps the plunger in the
retracted position. (See “Run Circuit—Theory of
Operation” on page 4-33.)