86
injectors are mounted in the
intake manifold. The injectors
are fired individually in the
same sequence as the spark
plug firing sequence.
Short (circuit)
A fault condition: an unwanted
connection of one electric
circuit to another causing a
change in the normal current
flow path.
Solenoid
A device to convert an electrical
current to mechanical motion. It
consists of a coil of wire with a
movable metal rod in the
center. When power is applied
to the coil, the resulting
electromagnetism moves the
rod and performs some
mechanical action. The ECU
often uses solenoids to switch
vacuum lines on and off. This
allows the ECU to control
vacuum operated devices such
as an EGR valve. Fuel injectors
are another type of solenoid.
SPK
Abbreviation for Spark.
SPK-BVSV
Spark Control Bimetallic
Vacuum Switching Valve.
Starter Relay
Supplies power to the starter
motor.
Starter Signal
This signal notifies the ECU
when the engine is cranking.
Stepper Motor
A special type of electric motor
with a shaft that rotates in small
“steps” instead of a continuous
motion. A certain sequence of
frequency type signals is
required to step the motor
shaft. A different signal
sequence will step the shaft in
the opposite direction. No
signals keeps the shaft still in
position. A constant signal drive
will continuously rotate the
shaft. The shaft is usually
connected to a threaded
assembly which moves back
and forth to control things such
as idle speed. The engine
computer sends the correct
signals to the motor for control.
TA Sensor
(Temperature - Air.) See Air
Temperature Sensor.
TBI
See Throttle Body Injection.
TCCS
See Toyota Computer Control
System.
TDC
See Top Dead Center.
TDC/CRANK/CYL
or TDC/CRANK
This is a group of three sensors
usually located within the
Distributor. The TDC signal
determines timing while
cranking and detects an
abnormal crank angle signal.
The CRANK signal represents
engine RPM. The CYL signal
represents the NO.1 cylinder
position. The ECU uses these
signals for ignition and fuel
injector control.
Thermistor
A resistor whose resistance
changes with temperature.
Thermistors are used as
sensors for vehicle coolant and
manifold air temperature. The
resistance decreases as
temperature goes up.
Throttle Angle
Sensor
See Throttle Position Sensor.
Throttle Body
A device resembling a
carburetor but using Electronic
Fuel Injector(s) in place of the
Fuel circuit of a carburetor.
Throttle Body
Injection (TBI)
A fuel injection system
consisting of fuel injector(s)
located in a Throttle Body.
Throttle Position
Sensor or Switch
(TP or TPS)
The throttle position sensor
consists of a Potentiometer or a
Switch that notifies the ECU of
throttle position.
Throttle Sensor
See Throttle Position Sensor.
Throttle Valve Idle
switch
Signals the ECU when the
throttle is in the idle position.
Top Dead Center
(TDC)
When a piston is at its
uppermost position in the
cylinder - maximum
compression.
Toyota Computer
Control System
(TCCS)
A computerized unit that
controls engine operation and
other systems using information
received from sensors.
TPS
See Throttle Position Sensor.
TW Sensor
(Temperature - Water.) See
Coolant Temperature Sensor.
Vacuum Switch or
Sensor
A switch or sensor who’s output
depends on vacuum.
Vacuum
Switching Valve
(VSV)
Provides vacuum to appropriate
system or device.
Valve Timing Oil
Pressure Switch
This switch signals the ECU
when the Variable Valve Timing
Electronic Control (VTEC)
system is operating.
Variable Valve
Timing Electronic
Control (VTEC)
A system of controlling the
opening of the intake valves.
The VTEC Spool Valve is used
to control the valves.
Vehicle Speed
Pulser
See Vehicle Speed Sensor.
Summary of Contents for Code Scanner CP9025
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