Simplicity AGCO Allis 500 Series, Service And Repair Manual

Page: 66 / 201

7 Electrical System Service
General Information
7 - 2
WARNING
Before beginning any service work, turn the PTO
off, set the parking brake, turn the ignition switch
off, remove the key, disconnect the spark plug
wire, and disconnect the negative battery cable.
GENERAL INFORMATION
SECTION CONTENTS
Section 7 has seven sub-sections:
General Information–Contains a general overview of
the electrical system, principles of operation, and defini-
tions of basic electrical terms.
Exploded View Diagrams–Three dimensional illustra-
tions of the electrical system components.
Full Electrical System Wiring Diagram–Schematic of
the electrical system.
Linear Circuit Diagrams–Linear diagram showing elec-
trical current path with the key switch in its three posi-
tions.
Component Location and Replacement–Shows the
location of electrical components and explains how to
remove and replace them.
Troubleshooting Flow Chart–Provides an ordered
checklist of component tests to solve common electrical
problems. Includes references to specific component
test procedures.
Component Tests–Testing procedures for specific com-
ponents.
INTRODUCTION
Tools Needed
• VOM (Volt-Ohm meter, multi-meter, or equivalent)
• Test Light.
• Jumper wires with clips at both ends.
Electrical System Changes
Early and later model Regents may have different electri-
cal components. However, the basic configurations and
troubleshooting procedures given in this section still
apply.
System Description
The tractor has three basic electrical circuits correspond-
ing to the three positions of the key switch: START,
RUN, and OFF.
• START sends battery power to two sub-circuits:
1) sends power to the safety switches (PTO, foot
pedal, and transmission switches). If all safety
switches are closed the solenoid is activated sending
power to the starter.
2) sends power to the fuel solenoid, headlight
circuit, etc.
• RUN sends battery power to two sub-circuits:
1) connects the alternator to the battery through key
switch. The alternator coil feeds power back into the
battery for recharging.
2) sends power to the fuel solenoid, head lights, and
PTO clutch switch.
• OFF grounds the engine ignition coil through the igni-
tion switch, preventing ignition system sparking. The
safety interlock system creates its own “OFF” circuit if
an unsafe situation exists. The safety system
grounds the ignition coil using a combination of:
1) the PTO switch and seat switch
or
2) the brake pedal switch and seat switch
if an operator is not present in the seat.
PRINCIPALS OF OPERATION
Ignition System
When the ignition switch is turned to OFF, the ignition
circuit closes and grounds the ignition coil stopping the
engine by terminating spark.
When the ignition switch is in the RUN position, the igni-
tion circuit is open, allowing the engine to run.
Charging System
While the engine is running, current flows from the alter-
nator to the positive battery post and charges the battery.
The circuit breaker, normally closed, opens if the circuit
is shorted.