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

www.TechnicalBooksPDF.com
Electrical Diagrams and Wiring 125
Continues on
page 22-18
DASHBOARD WIRE HARNESS B
3 4 5 6 7
2
1
PASSENGER’S
UNDER-DASH
FUSE/RELAY
BOX
8
Figure 6-61. DaimlerChrysler installation diagram.
(DaimlerChrysler Corporation)
9
14
13
12
11
10
Figure 6-63. Acura installation diagram. (Courtesy of
American Honda Motor Co., Inc.)
Figure 6-62. GM installation diagram. (GM Service
and Parts Operations)
Cars use some special types of wire, especially
in battery cables and ignition cables. Terminals
and connectors join different wires in the car;
these can join single wires or 40 or more wires.
Part of every automotive circuit is the ground path
through the car’s frame and body. The battery terminal
that is connected to ground determines the
electrical system’s polarity. Most modem automobiles
have a negative-ground system.
Multiplexing simplifies wiring by sending two
or more electric signals over a single channel.
Along with conductors, connectors and the
ground path, each automotive circuit has controlling
or working parts. These include switches,
relays, solenoids, buzzers and motors.
There are three types of electrical circuit diagrams:
system, schematic, and installation. System
diagrams typically present an overall view, while
schematic diagrams isolate a single circuit and are
Figure 6-64. A typical GM power distribution
schematic. (GM Service and Parts Operations)
more useful for troubleshooting individual problems.
Installation diagrams show locations and
harness routing. To better understand these diagrams,
a variety of electrical symbols are used to
represent electrical components. Other tools to aid
in successfully reading these diagrams are the
color coding and the circuit numbering of wires,
which identify the wire and its function.
Manufacturers publish diagrams of each vehicle’s
electrical systems, often using these color codes
and circuit numbers. A technician cannot service
a circuit without knowing how to read and use
these diagrams.