Service Manual

400XT Series Tractor Service Manual 4 - 1
ELECTRICAL SYSTEMS
Electrical Systems
Two things happen when turning the ignition switch to
the “START” position. (1) Current flows from the
ignition switch through the PTO (Power Take Off)
switch, brake switch, seat switch, and activates the
interlock relay, which sends voltage to the coil of the
starter solenoid. The solenoid actuates and allows
voltage to the starter motor of the engine. (2) At the
same time, with the ignition in the “START” position,
current will flow to the kill relay, which activates and
takes the electronic ignition ground wire off of ground to
allow the engine to have spark.
Once you have the tractor running, you can now
engage the PTO (Power Take Off) switch which will
engage the electric clutch for the mower or
attachments only if you are in the seat, activating the
seat switch. Anytime you vacate the seat with the
electric clutch activated for the mower, the seat switch
will open and cut off voltage to the kill relay, which will
deactivate and ground the electronic ignition and stop
the engine. If you vacate the seat with the PTO switch
disengaged and the park brake engaged, the engine
will continue to run.
The following electrical section covers most of the
electrical components used on the 400XT Series
Garden Tractors. It covers each electrical
component’s purpose, how it works, testing procedures
and location on the tractor. To help you further to
troubleshoot electrical problems, the Riding Products
Electrical Demystification Guide, Form 492-4761 is
available with complete wiring and circuit diagrams to
help diagnose electrical problems.
Relay
Purpose
The 400XT Series Garden Tractors use relays to direct
current flow to different areas of the tractor. The most
complex models have three relays: cruise control relay,
interlock relay, and a kill relay. Electrically, they all
operate the same.
Location
The relays are located on the firewall of the tractor
(Figure 218).
Figure 218
MVC-831F
How It Works
A relay is an electrically actuated switch.
1. Coil: Terminals 85 and 86 are connected to a coil.
Applying 12 volts to these terminals energizes the
coil turning it into an electromagnet.