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

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124 Chapter Six
and color, components, connector and ground
references, and references to other circuits when
necessary. In addition, a quick summary of system
operation is provided to explain what should
happen when the system is working properly.
GM and includes a power distribution diagram
as one of the first overall schematics for troubleshooting
(Figure 6-64). The power distribution
diagram represents the “front end” of the overall
electrical system. As such, it includes the battery,
starter solenoid or relay, alternator, ignition
switch, and fuse panel. This diagram is useful in
locating short circuits that blow fusible links or
fuses, because it follows the power distribution
wiring to the first component in each major circuit.
Figure 6-59. GM fuel-economy lamp circuit. (GM
Service and Parts Operations)
SUMMARY
Many of the conductors in an automobile are
grouped together into harnesses to simplify the
electrical system. The conductors are usually
made of copper, stainless steel, or aluminum covered
with an insulator. The conductor can be a
solid or single-strand wire, multiple or multistrand
wire or printed circuitry. The wire size or
gauge depends on how much current must be carried
for what distance. Wire gauge is expressed as
a number—the larger the number, the smaller the
wire’s cross-section.
Figure 6-60.
GM Cadillac Deville side marker lamp circuit. (GM Service and Parts Operations)