1. Objectives:
• Identify the basic components that make a vehicle function:
 Electrical Circuits
 Fuses
 Battery
 Starter Motor
 Fuel Pump
Introduction to Basic
Vehicle Diagnosis

2. Electrical Circuits allow electricity to flow along a given
path and usually contain the following elements.
Electrical CircuitsElectrical Circuits

3. Electrical CircuitsElectrical Circuits
Usually a battery, the power source
provides the energy.
Usually a battery, the power source
provides the energy.
PowerPower
SourceSource
Most circuits have a protective
device, such as a fuse, to prevent an
overload in case of a short circuit.
Most circuits have a protective
device, such as a fuse, to prevent an
overload in case of a short circuit.
ProtectiveProtective
DeviceDevice
Circuits can have a manual or
automatically controlled switching
device to turn a circuit on or off.
Circuits can have a manual or
automatically controlled switching
device to turn a circuit on or off.
SwitchSwitch
ContinueContinue

4. A car’s headlight works because of
electrical circuits.
When the headlight switch is turned
“off”, the electrical circuit is open, and
power cannot flow to the bulb. As a
result, the light goes out.
Click the headlight
switch to turn “on”
the lights.
Electrical CircuitsElectrical Circuits

5. Electrical CircuitsElectrical Circuits
When the headlight switch is “on”,
electricity can flow from the car’s
battery to the light bulbs, causing the
bulbs to illuminate.
Click the headlight
switch again to
continue.

6. FusesFuses
Fuses are safety devices
that protect the components
of an electrical circuit. They
are designed to be the first
point of failure for a circuit.

7. FusesFuses
To illustrate:
If a circuit were to experience a
“short,” too much power would
be introduced into the circuit and
it would damage the circuit’s
components (lights, computers,
air conditioners, etc).
By having a fuse, the damage is
isolated to the inexpensive fuse
instead of to a more costly
component.
Click the fuse toClick the fuse to
simulate asimulate a “short“short
circuit”.circuit”.

8. FusesFuses
Notice how the fuse broke when
it was overloaded.
The fuse absorbed the energy
and broke the connection with
the rest of the circuit before it
could cause damage to other
more important and expensive
components.

9. A Battery is a power source
that delivers electricity to
BatteryBattery
Radio
Headlights
Instrument Panel
Starter

10. The Starter Motor is the vehicle component that causes the engine
to start. It converts the battery’s electrical energy into mechanical
energy that allows the engine to begin generating power.
Starter MotorStarter Motor

11. Traditional vehicle engines run on gasoline.
A Fuel Pump is the component that pumps gas from the gas
tank to the engine.
Fuel PumpFuel Pump