Skytrak 6042 Service Manual User Manual download pdf (Page 450)

Electrical System

9.80

Model 6042 Legacy Origin 7/02

9.10 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

(Fig. 9-38, 1) must be in the START (2) position, the park

brake switch must be in the ON position and the transmis-

sion shift control switch (travel select lever) must be in the

NEUTRAL (center) position.

When the ignition key switch (Fig. 9-38, 1) is turned to

the START (2) 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.

9.10.1 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 (Fig. 9-38, 1) is turned to the

START (2) position, current flows through contacts in

the ignition key switch to the park brake switch.

Figure 9-38 Ignition Key Switch Positions

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 (Fig. 9-38, 1) is

released, it returns to the RUN (3) 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.

9.10.2 Starter

The starter (Fig. 9-39, 1) is located on the left side of the

engine (the left side of the vehicle).

Figure 9-39 Starter Location

The starter operates when the attached starter solenoid

engages a gear on the starter pinion shaft to mesh with

the flywheel, and the starter pinion and gear begin to spin,

in turn rotating the flywheel, crankshaft and related

components within the engine.

The starter is grounded indirectly via the negative (–)

battery cable. The cable (Fig. 9-39, 7) is routed from the

battery to the starter housing where it attaches to the

engine.

MA10,0010

MA8420

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Skytrak 6042 Service Manual User Manual Page 450

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