Service Manual

627333-A 6-1
General Information
GENERAL INFORMATION
INTRODUCTION
The electrical system can be divided into four sections:
•Engine;
• Operator’s Station;
• Electro Hydraulic;
• Lighting.
Current to electrical systems is provided by a high output
alternator with a built-in voltage regulator. These high
output alternators are needed because, under certain
conditions, very high amperage demands are required.
The 12-volt batteries wired parallel have a double
negative ground-one to engine frame and one to starter.
A double connection is provided to ensure a reliable
ground.
BASIC TROUBLESHOOTING
PROCEDURES
In troubleshooting electrical circuits the first step is to
familiaize yourself with the components, wire routing and
connections of the circuit. This can be aided by studying
the wiring diagrams in the operator’s or service manual.
Each electrical circuit on the machine is isolated to show
the wire connections and components used. Most
diagrams give a visual approximation of the components
to aid in identifying unfamiliar parts.
If a module or other electrical component is completely
dead, first check the diagram for the correct condition,
i.e., ignition switch on, clutches engaged, ect. Check for
obvious failure areas like fuses, unhooked connection or
broken wires. The ground circuit can also become
defective because of a broken wire or poor connection to
the frame. Most voltmeter probes are small enough to
insert into the back side of the electrical connectors so
the supply voltage to a module can be checked without
disconnecting it the harness.
The greatest percentage of defective connections occur
at or near the connectors themselves. Visually check to
see that terminals are completely inserted into the
housing (no terminal should be exposed above the
surface of the connector). This difficult in some
connectors below the console and may require removal
of the outside cover panel. If the locking tang on the
terminal is damaged and will not retain the terminal in
the connector, a new terminal from the electrical service
kit will need to be installed. Some terminals may just
require the locking tang on the terminal be reformed so it
will catch the appropriate step in the housing.
Immediately behind the connectors is another potential
failure area. This is increased if the wires are flexed or
sharply kinked. Moving the wires from side to side may
produce intermittent contact and locate the general area
of failure.
Corrosion of the terminals is possible as the machine
ages. In some cases simply disconnecting and
reconnecting a connector will solve a poor connection
problem. Heavy corrosion of terminals may occur since
the machine is exposed to or stored with fertilizer of
other corrosive products. This will require replacement of
the affected terminals to provide reliable connections
over a long period of time.
In troubleshooting a new machine or an electrical
system that has never functioned correctly, check for the
possibility that wires in the connector may be crossed or
that wires in the connector may be inserted in an
incorrect terminal where no continuity between
harnesses exists. Wire colors, functions and terminal
numbers (on numbered connectors) are listed in the
operator’s service manual under Electrical Circuits.
Wires that have been exposed to oil or sunlight may
require some of the harness covering to be removed to
aid in identifying the correct color.