Automotive Electrical and Electronic Systems Classroom Manual Fifth Edition Update by John F. Kershaw

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Electrical Diagrams and Wiring 105
Figure 6-24. The instrument panel switch in this two-speed windshield wiper circuit has two sets of contacts
linked together, as shown by the broken line. The Park switch is operated by mechanical linkage from
the wiper motor armature. (DaimlerChrysler Corporation)
Figure 6-25. This starting and ignition switch has two
sets of contacts linked together by the dashed line.
Triangular terminals in the start (ST) position indicate
that this position is spring-Ioaded and that the switch
will return to RUN when the key is released.
(DaimlerChrysler Corporation)
Figure 6-26. A coolant temperature switch in
its normally open position.
Relays
A relay is a switch that uses electromagnetism to
physically move the contacts. It allows a small
current to control a much larger one. As you
remember from our introduction to relays in
Chapter 2, a small amount of current flow
through the relay coil moves an armature to open
or close a set of contact points. This is called the
control circuit because the points control the
flow of a much larger amount of current through
Figure 6-27.
A mercury switch is activated by motion.