SkyTrak 8042 Service Manual - Manual (Page 786)

9.195 Model 8042, 10042, 10054 Legacy Rev. 10/03
Electrical System
9.9 ENGINE START CIRCUIT
The purpose of the engine start circuit is to energize the
starter solenoid and engage the starter motor to start the
engine. To start the engine, the ignition key switch must
be in the START (1) position, the park brake switch must
be in the ON position and the transmission shift control
switch (travel select lever) must be in the NEUTRAL
(center) position.
When the ignition key switch is turned to the START (1)
position, and with the transmission in (N) NEUTRAL, the
starting circuit activates the starter relay, starter solenoid
and fuel shut-off solenoid. The fuel shut-off solenoid
opens a valve that supplies fuel to the injection pump.
9.9.1 Starting Circuit
The starting circuit functions as follows:
1. Current from the battery flows through the positive
(+) battery cable to the starter solenoid.
2. Current then flows to the fuse box, through the main
fuse and to the ignition key switch.
3. When the key switch is turned to the START (1)
position, current flows through contacts in the
ignition key switch to the park brake switch.
4. If the park brake is set, current flows through
contacts in the brake switch to the neutral start
circuit.
5. If the transmission select lever is in (N) NEUTRAL,
current flows through the neutral start circuit to
energize the coil of the starter relay. The relay closes
internal contacts that allow current to flow to the
starter solenoid and starter.
6. The starter solenoid engages a gear on the starter
pinion shaft to mesh with the flywheel. The starter
pinion and gear begin to spin, in turn, rotating the
flywheel, crankshaft and related components within
the engine.
7. When the ignition key switch is initially turned, the
fuel shut-off solenoid opens a valve to supply power
to the fuel injection pump. As the starter rotates the
engine components, the fuel injection pump, and
related lines and injectors supply fuel to the
cylinders.
8. When the pistons compress the injected fuel, ignition
occurs, the engine starts and the starter pinion
retracts.
9. As the engine runs, it drives the alternator that
recharges the battery used during the starting cycle.
10. When the ignition key switch is released, it returns to
the RUN (2) position where it directs current to the
fuse panel that, in turn, distributes electrical current
for the operation of vehicle controls, gauges and
other equipment.
MA10,0010
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