Service Manual

Mid-Size Walk Behind Service Manual 8 - 3
ELECTRICAL
Note that there is a diagram on the side of the relay
and each terminal is numbered (Figure 215).
Location
The relays are located under the control panel on the
mid size mowers.
Figure 214
mvc-077
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.
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 215).
Figure 215
mvc-671x
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 terminal 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 a 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
terminals 30 and 87a as 12 VDC is applied and
removed from the terminal.