Simplicity AGCO Allis 400 Series, Service & Repair Manual

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5 Electrical Troubleshooting
General Information - Theory
5 - 2
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 Coronets may have different elec-
trical components. However, the basic configurations
and troubleshooting procedures given in this section still
apply. For instance: If the troubleshooting procedure
instructs you to test the clutch / brake pedal switch, and
your rider doesn’t have a clutch / brake pedal switch,
simply skip that step.
System Description
The rider has four basic electrical systems: ignition,
charging, cranking, and the safety interlock system.
• The ignition system, contained in the engine, is con-
nected through a harness from the magneto to the
ignition switch and interlock module.
• The charging system replenishes lost power to the
battery. The alternator supplies power through a
wiring harness that is connected to a circuit breaker,
and then to the battery.
• The cranking system provides the high energy need-
ed to start the engine. Current is drawn from the bat-
tery, through the solenoid, to the starter when the
ignition switch is activated.
• The safety interlock system incorporates safety cir-
cuits for safe starting, operation, and shutdown under
unsafe conditions. It consists of the neutral safety
switch, PTO switch, "Operator Present" seat switch,
clutch/brake switch, and the interlock module.
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 through a rectifier to the positive battery post and
charges the battery. The circuit breaker, normally
closed, opens if the circuit is shorted.
Cranking System
THE CRANKING SYSTEM IS COMPOSED OF:
the ignition switch, the solenoid, the safety interlock sys-
tem, and the starter.
CRANKING SYSTEM CURRENT PATH:
1. Current travels from the battery through the ignition
switch to the solenoid.
2. Current is passed from the solenoid to the safety
interlock system.
3. If all safety conditions are met, the safety interlock
system completes the circuit and activates the sole-
noid.
4. The activated solenoid sends power to the starter,
cranking the engine.
Safety Interlock System
The safety system can be divided into two sub-systems:
1) the Operator Present sub-system and
2) the Safety Starting sub-system.
1) OPERATOR PRESENT SUB-SYSTEM
The operator present sub-system grounds the engine
ignition module (killing the engine) if the operator leaves
the seat with the transmission engaged or the PTO
engaged.
The operator can leave his/her seat with engine running
ONLY if ALL of the following conditions are met:
Hydro Models
-the PTO disengaged, AND
-the parking brake engaged.
Gear Models
-the PTO disengaged, AND
-the ground speed control lever is in neutral.
2) SAFETY STARTING SUB-SYSTEM
The safety starting sub-system will prevent the engine
from cranking if an operator is not sitting in the seat. The
safety starting system will also prevent starting if the
transmission is engaged or the PTO is engaged.
The engine will crank ONLY if ALL of the following con-
ditions are met:
-the operator is in the seat, AND
-the PTO is disengaged, AND
-the groundspeed control lever is in neutral, AND
-(hydro models only) the clutch / brake pedal is
depressed.