Electrical Components
Identification And Testing
Chapter 1/3/4/5
(Jumping around today..hang on!)
Resistors. P 6
•	Resist current flow
•	Wattage Ratings  = Size of total power it can handle
•	Color bands
•	Measured in Ohms..
•	Variable designs
•	Potentiometer = Volume control or TPS
•	Rheostat = Variable Dimmer.
•	Mainly internal to most devices
•	2 Wires, use OHM function to test, or Voltage Drop...

Diodes - p36
•	Act as a check valve
•	Allow current to flow in direction of arrow
•	Is a semi conductor
•	Made of an anode and cathode
•	See fig 3-7
•	Polarity is important!

Diodes
•	Act as a “gate”
•	Allow current flow in only one direction
•	Can be tested with the meter on the DIODE test function
•	Zener design…
•	LED - Light Emitting Diode

Capacitors p7
•	Act like a very short term battery
•	Can absorb voltage spikes and dips
•	Rated in Farads
•	Polarity is important!

Switches p 101
•	Can turn a circuit ON or OFF
•	May be NO or NC
•	Single Pole Design
•	SPST? SPDT?
•	Single Pole Single Throw
•	Single Pole Double Throw
•	“Gang” Design
•	Mercury Design - Senses Movement

Relays p 14 and p 39
•	“Electric Switch”
•	Takes a small current to “move” an internal switch
•	4-5 contacts
•	2 contacts run internal coil
•	2 contacts are the switch
•	Uses a small internal magnetic field to move switch open or closed
•	Many MANY uses in a vehicle.
•	May have a despike resistor or diode
Relay Slides…
Solenoids p 14
•	Electromagnetic Device
•	Uses current inside a coil to move a central core
•	This core can allow vacuum, fuel, air, etc.. To pass through a tube (fuel injector!)
•	Or the core can “push” or “pull” a lever (door locks, starter solenoid)
•	2 wires for internal coil
Transistors p43
•	Work “like a relay”, however no moving parts.
•	NPN or PNP design
•	Base, Emitter, Collector
•	Photo Transistor - Senses Light
Circuit Protection Devices
•	Fuses
•	Links
•	Breakers
•	Test with test light or meter.
•	REMOVE FUSE FROM CIRCUIT IF TESTING WITH CONTINUITY TEST!