Testing Switches - MTD 700 Series Professional Shop Manual

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Testing switches

• Refer to the "COMPONENTS" section of this chapter that describes the function of the individual switches
to be tested.
• Switches can be tested "hot" by looking for voltage at the appropriate posts. This is not definitive, 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 continuity test.
1. Understand the internal functions of the switch. Key switches and PTO switches can be fairly complex.
2. Isolate the switch from the rest of the circuit.
3. Test each pair of terminals for continuity in all modes of switch operation: at-rest, and actuated.
4. Many switches on Cub Cadet equipment are typed by their at-rest state: Normally Open, Normally Closed,
Common.
Normally Closed
switch element:
Spades marked: "NC"
www.mymowerparts.com
Normally Open
switch element:
Spades blank
Figure 7.59
• 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 circuit
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 termi-
nals associated with Normally Closed contacts 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 7.59.
Electrical
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