1. Actuators
Chapter Lesson 5

2. Actuators
Devices that allow the computer to do work and alter the operation of other components
Actuators may be found anywhere on the modern automobile

3. Actuator Classifications
Actuators can be grouped into the following categories:
solenoid
relay
servo motor
display device
control module

4. Actuator Classifications

5. Actuator Operation
When the computer turns on an actuator, it normally provides the device with a ground circuit
Current can then operate the actuator

6. Actuator Operation

7. Solenoid Operation Computer grounds the solenoid circuit
Current flows through the solenoid winding
A magnetic field moves the plunger mounted in the solenoid windings
Plunger movement is used to operate a device
fuel injectors, vacuum valves, door locks, etc.

8. Solenoid Operation (Automatic Door Locks)

9. Relay Operation Computer grounds the relay coil windings
Low current flows through the relay windings
Relay coil field will then pull the mechanical contacts closed, allowing high current to flow to the load

10. Relay Operation

11. Servo Motor Operation
Computer can ground the motor circuit, turning the motor on and off or reversing motor rotation as needed
Some servo motors are simply reversible dc motors
these motors turn a threaded mechanism to produce controlled movement of a part

12. Specific coils can be energized to attract and stop the armature
Servo Motor Operation
Specific coils can be energized to attract and stop the armature

13. Specific Actuators Common actuators used on modern vehicles include:
Fuel injector
solenoid valve that controls fuel flow
Fuel pump
electric motor-driven pump

14. Specific Actuators Idle air solenoid Idle speed motor EGR solenoids
controls airflow into the engine to control idle speed
Idle speed motor
reversible dc motor that opens and closes the throttle valve to control idle speed
EGR solenoids
open and close small ports to control exhaust gas flow back into the engine

15. Specific Actuators Canister purge solenoids Door lock motors
control vacuum flow to draw fuel vapors from the fuel tank into the engine for burning
Door lock motors
solenoids that move latch mechanisms to lock or unlock the doors
Electric seat motors
reversible dc motors that move the seat into the desired position

16. Specific Actuators Ignition coil Ignition module
changes low voltage into high voltage that operates the spark plugs
Ignition module
uses computer signals to control the operation of the ignition coils