Service Manual User Manual

Electrical System
10-37
Model 3606 • Origin 10/99
10.5.1 Fuse and Relay Replacement
Shut off the engine and disconnect the negative (-) bat-
tery cable at the negative (-) battery terminal (Fig. 10– 23)
before checking the electrical system. Use an ohmmeter
to check the resistance of wires and components.
Figure 10– 23. Disconnect the negative (-) battery cable.
Different fuse and relay panels exist. Vehicles with
serial
number 8249 and before
use the fuse and relay panel
shown in Fig. 10– 24. Vehicles with
serial number 8250
through 9398
use the fuse and relay panel shown in Fig.
10– 26. Vehicles with
serial number 9399 and after
use
the fuse and relay panel shown in Fig. 10– 27.
Before checking a malfunctioning electrical circuit, exam-
ine the applicable wiring diagram to help identify the
components involved. Noting whether other components,
including hydraulic system components, related to the
circuit are functioning properly can often aid in identifying
problems. When several components or circuits fail at
one time, the problem is probably related to a poor
ground connection, because several circuits may share
that same connection. Examine the appropriate ground
connection(s) and make sure a contact capable of con-
ducting full voltage is available.
10.6 ENGINE START CIRCUIT
When the ignition key switch (Fig. 10– 25) is turned to
START the engine with the transmission in NEUTRAL
(N), the starting circuit activates the starter relay, starter
solenoid, and fuel run solenoid. The fuel run solenoid
opens a valve that supplies fuel to the injection pump.
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, to terminal "1" of the ignition switch.
Figure 10– 24. Vehicles with
S/N 8249 and before
use the
fuse and relay panel shown above.
Figure 10– 25. Ignition key switch positions.
3. When the key is turned to the START position (Fig.
10– 25), current flows through contacts in the ignition
switch to the park brake switch.
OS1040
Negative (-)
Terminal
Vehicles Stamped with
S/N 8249 and Before
OS1113
Hourmeter
Neutral Relay/Starter
Fuel Shut-off
Display Panel
Main Fuse
Switch Lamps
Stabil-TRAK Solenoid
Stabilizer Lock Relay
Perkins Cold
Start (optional)
Neutral
Sense
Logic
Panel
Trans-
mission
Relay
Horn
Steer
Solenoids
Park Brake
Sense
Trans-
mission
Solenoids
Trans. Relay 1
Forward Relay
Reverse Relay
Neutral Relay
Trans. Relay 2
Trans. Relay 3
Boom Switch
Stabilizer Lock Relay
OF0390
OFF
RUN
PREHEAT
START