Relay (Kill Relay); Purpose; Location; How It Works - Toro Lawn-Boy TimeCutter Z Series Service Manual

ELECTRICAL SYSTEM
Electrical System
Two things happen when turning the ignition switch to
the "START" position: (1) Current flows from the
ignition switch to the starter solenoid coil terminal. (2)
At the same time, current will flow through the PTO
(Power Take Off) switch in the OFF position, through
both the brake switches, in the OFF or PARK position,
to the coil terminal of the interlock relay (kill relay). The
interlock relay (kill relay) activates and takes the engine
electronic ignition ground wire off ground to allow the
engine to spark and grounds the starter solenoid to
engage the starter motor of the engine.

Relay (Kill Relay)

Purpose

The relay used in the TimeCutter Z is used to connect
or disconnect the engine electronic ignition and starter
solenoid from chassis ground.

Location

The relay is located in front of the engine (Figure 77).
5

How it Works

Figure 77
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.
5 - 2
2. Switch: Terminals 30, 87, and 87a are actually
part of a single pole, double throw (SPDT) switch.
Terminal 30 is the common lead. The switch is
spring loaded so that 30 and 87a are connected
when the coil is not energized. When the coil is
energized, the switch is "thrown" and 30 and 87
are connected (Figure 78).

Testing

1. Disconnect the relay from the harness.
2. Verify the coil resistance between terminals 85
and 86 with a multimeter (ohms setting).
Resistance should be from 70 to 90 ohms. There
should be continuity between terminals 87a and
30.
3. Connect multimeter (ohms setting) leads to relay
terminals 30 and 87. Ground terminal 86 and
apply +12 VDC to 85. The relay should make and
break continuity between terminals 30 and 87 as
12 VDC is applied and removed from terminal 85.
4. Connect multimeter (ohms setting) leads to relay
terminals 30 and 87a. Apply +12 VDC to terminal
85. With terminal 86 still grounded, the relay
should break and make continuity between
mvc-190
terminals 30 and 87a as 12 VDC is applied and
removed from terminal.
Figure 78
mvc-671
TimeCutter Z Service Manual