SkyTrak 6036 Service Manual - Manual (Page 276)

Section 10. Electrical System
10-14 Model 6036/6036T S/N 9B0500 thru 14833
10. When the ignition key is released after start-
ing, it returns to a neutral position where it
directs current to circuit breakers which
distribute current for the operation of forklift
controls, gauges and equipment.
11. When the ignition key is turned to the OFF
position, contacts within the ignition switch are
opened and the fuel run solenoid valve closes,
blocking the flow of fuel to the fuel injection
pump.
10.5.1 Testing Starter in Forklift
General Starter Checks
If nothing happens when you turn the ignition key:
1. The 40 A circuit breaker may be open and
require replacement;
2. There may be a defect in the ignition switch,
ignition wiring, or starter solenoid;
3. Check the condition of the batteries as de-
scribed in paragraph 10.6.2. Clean the battery
posts and the connectors at each end of the
battery cables. Also check the ground cable
between the starter mounting bolt and the
frame.
4. Check for broken wires and damaged insula-
tion on the wires. Replace all broken or
damaged wiring.
5. Check all connections at the starter solenoid,
key switch, and wiring harness plugs. Clean
and tighten all connections.
6. If the starter still does not run after you do
these checks, check the starting circuit.
10.5 STARTING CIRCUIT
When you turn the ignition key to start the engine
with the transmission in neutral, the starting circuit
actuates a starter relay, a starter solenoid, a
starter and a fuel run solenoid. The fuel run
solenoid opens a valve which supplies fuel to the
injection pump.
PERKINS ONLY: When starting in a cold environ-
ment, turning the key to a position between run
and start for a few moments before starting, will
supply current to a thermo start plug in the intake
manifold. The plug ignites a fuel-air mixture in the
intake manifold to facilitate cold weather starting.
The starting circuit functions as follows:
1. Current from the batteries (1, Fig. 10.8) flows
through the positive battery cable (2) to the
starter solenoid.
2. It then flows to circuit breaker (3) and to
terminal “1” of the ignition switch (4).
3. When the key is turned to the START position,
current flows through contacts in the ignition
switch to the emergency brake switch (5).
4. If the emergency brake is set, current flows
through contacts in the brake switch to the
neutral start switch (6).
5. If the transmission select lever is in neutral,
current flows through contacts in the neutral
start switch to energize the coil of the starter
relay (7). The relay closes contacts which
allow current to energize the starter solenoid
and operate the starter.
6. When the solenoid and related mechanisms
cause the starter pinion to engage a gear on
the flywheel, the starter motor rotates the
gear, crankshaft and related components in
the engine.
7. When the ignition key was turned in step 3,
the fuel run solenoid opened a valve to supply
fuel to the fuel injection pump. As the starter
rotated the engine components, the fuel
injection pump and related lines and injectors
supplied fuel to the cylinders.
8. When the pistons compress this injected fuel,
ignition occurs, the engine runs and the starter
pinion retracts.
9. As the engine runs, it operates an alternator
which recharges the battery which was used
during the starting cycle.
Starter Circuit Checks
1. With the key turned to the RUN position, use a
jumper wire to try shorting the positive battery
cable to the solenoid starter connection. If the
starter now cranks, the problem is in the wiring
circuit. If the solenoid fails to “click” the starter
is probably defective.
2. If you hear a “whirring” noise but the engine
does not crank, the starter is spinning but is
not engaging the flywheel. The starter drive or
solenoid that pushes the drive forward to
engage the flywheel may be defective. Miss-
ing teeth on the flywheel can also prevent the
starter from cranking the engine.
3. If the starter only “clicks”, it might indicate
discharged batteries or a loose or corroded
battery cable connection(s). Check battery
charge and condition first.