Actuators Chapter 17 Lesson 5

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

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

Actuator Classifications

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

Actuator Operation

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.

Solenoid Operation (Automatic Door Locks)

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

Relay Operation

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

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

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

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

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

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