16 Section 1 Introduction to Automotive Technology
Tech Tip
Most late-model hybrid vehicles do not need
conventional starting and charging systems
with a separate alternator and starting motor.
Instead, hybrids use a motor-generator to
recharge the batteries and “crank the engine”
for start-up. This reduces vehicle weight and
complexity for added fuel economy.
Charging System
The charging system is needed to replace electri-
cal energy drawn from the battery. With a 12-volt
battery, a belt-driven alternator forces electric cur-
rent back into the battery.
When the engine is running, a drive belt spins the
alternator pulley. The alternator can then produce
electricity to recharge the battery and operate other
electrical needs of the vehicle. A voltage regulator,
usually built into the alternator, controls the voltage
and current output of the alternator.
Lighting System
The lighting system consists of a vehicle’s interior
and exterior lights and all the components that oper-
ate them (fuses, wires, switches, relays, etc.). The
exact circuit and part confi gurations will vary from
one model to another.
The exterior lights typically include the head-
lights, turn signals, brake lights, parking lights,
backup lights, and side marker lights. The interior
lights include the dome light, trunk light, instru-
ment panel lights, and other courtesy lights.
Cooling and Lubrication Systems
The cooling and lubrication systems are designed
to prevent engine damage and wear. They are vital
systems that prevent the engine from self-destructing.
The cooling system maintains a constant engine
operating temperature. It removes excess combus-
tion heat to prevent engine damage and also speeds
engine warm-up. Look at Figure 1-16.
The water pump forces coolant (water and anti-
freeze solution) through the inside of the engine,
hoses, and radiator.
The coolant collects heat from the hot engine
parts and carries it back to the radiator. The radia-
tor allows the coolant heat to transfer into the out-
side air. An engine fan draws cool air through the
radiator.
The thermostat controls coolant fl ow and engine
temperature. It is usually located where the top radi-
ator hose connects to the engine.
The lubrication system reduces friction and wear
between internal engine parts. It circulates clean,
fi ltered oil to high-friction points in the engine,
such as bearings, camshaft, crankshaft, and pistons.
The lubrication system also helps cool the engine
by carrying heat away from high-friction points in
the engine.
Exhaust and Emission Control Systems
The exhaust system quiets the noise produced
during engine operation and routes engine exhaust
gases to the rear of the vehicle body. Figure 1-17
illustrates the basic parts of an exhaust system. Trace
the fl ow of exhaust gases from the engine exhaust
manifold to the tailpipe. Learn the names of the
parts.
Various emission control systems are used to
reduce the amount of toxic (poisonous) substances
produced by an engine and fuel system. Some sys-
tems prevent fuel vapors from entering the atmo-
sphere (air surrounding the earth). Other emission
control systems remove unburned and partially
burned fuel from the engine exhaust. Later chapters
cover these systems in detail.
Computer Ignition
key switch
Flywheel
Starter
Fuse box
Battery
Alternator
Drive
belt
Charging/Starting Systems
Figure 1-15. Note the location of basic parts of conventional
starting and charging systems. These parts are eliminated in
hybrid vehicles with the motor-generator.