Table of Contents
Advertisement
11.
Testing switches:
•
Refer to the "COMPONENTS" section of this
chapter that describes the function of the individ-
ual switches to be tested.
•
Switches can be tested "hot" by looking for volt-
age at the appropriate posts. This is not defini-
tive, since the source of the voltage is not always
confirmed. Checking for voltage does not work
on switches that work by providing a ground
path to the magneto primary windings or a solid
state control device.
•
The most valid way to test switches is a conti-
nuity test.
11a. Understand the internal functions of the
switch. Key switches and PTO switches
can be fairly complex.
11b. Isolate the switch from the rest of the cir-
cuit.
11c. Test each pair of terminals for continuity in
all modes of switch operation: at-rest, and
actuated.
11d. Many switches on Cub Cadet equipment
are typed by their at-rest state: Normally
Open, Normally Closed, Common.
•
Normally Open (N.O.) contacts do not complete
a circuit when the switch is at-rest (plunger
extended). They close to complete a path
through the switch when the plunger is
depressed.
•
Normally Closed (N.C.) contacts complete a cir-
cuit when the switch is at-rest (plunger
extended). They open to break the path through
the switch when the plunger is depressed.
•
Some Cub cadet switches contain more than
one pair of contacts. The same switch housing
can contain normally open and normally closed
switch elements.
•
When testing a switch that contains more than
one set of contacts (elements), the male spade
terminals associated with Normally Closed con-
tacts will be stamped "N.C."
•
The male spade terminals that are associated
with each-other face each-other broad-surface
to broad surface. See Figure 7.45.
Normally Closed
switch element:
Spades marked: "NC"
12.
Diodes
What is a diode? A diode acts like a one way
valve, allowing current to flow in only one direction.
See Figure 7.46.
Silver band
(-)
electrons flow from the negative to the positive.
•
Which way does this electrical check-valve
work? There will be a band on one end of the
diode. The band indicates the negative side of
the diode
•
Most DMMs have the ability to test a diode.
139
ELECTRICAL SYSTEM
Normally Open
switch element:
Spades blank
Figure 7.45
(+)
Figure 7.46
Advertisement
Table of Contents
