Actron CP9035 Insrucciones página 50

REFERENCE GLOSSARY
center. When the power is applied to
the coil, the resulting electromagnetism
moves the rod and performs some
mechanical action. The PCM often
uses solenoids to switch vacuum lines
on and off. This allows the PCM to
control vacuum operated devices such
as the EGR valve. Fuel injectors are
operated by another type of solenoid.
ST:
Short Term fuel trim.
Stepper Motor:
A special type of electric motor with a
shaft that rotates in small "steps"
instead of continuous motion. A certain
sequence of frequency-type signals is
required to step the motor shaft. A
different signal sequence will step the
motor in the opposite direction. No
signal maintains current shaft 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 bypass air
flow (see "IAC" definition).
TBI:
Throttle Body Injection. A fuel injection
system having one or more injectors
mounted in a centrally located throttle
body, as opposed to positioning the
injectors close to an intake valve port.
TBI is also called Central Fuel Injection
(CFI) in some vehicles.
TDC:
Top Dead Center. When a piston is at
its uppermost position in the cylinder.
At this point, it is generating maximum
compression.
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, sending a voltage signal to the
PCM where it is converted to a
8-9
temperature measurement.
Throttle Body:
A device which performs the same
function as a carburetor in a fuel
injection system. On a throttle body
injection (TBI) system, the throttle body
is both the air door and the location of
the fuel injectors. On port fuel injection
systems (PFI, MPFI, SFI, etc.) the
throttle body is simply an air door. Fuel
is not added until the injectors at each
intake port are activated. In each case,
the throttle body is attached to the
accelerator pedal.
TPS:
Throttle Position Sensor. This is a
rotary-type potentiometer connected to
the throttle shaft. It has a voltage signal
output which increases as the throttle
is opened. This sensor is used by the
PCM for idle speed, spark advance,
fuel delivery, emission systems, and
electronic automatic transmission
control.
TTS:
Transmission Temperature Sensor. A
thermistor — a sensor whose resis-
tance decreases with increases in
temperature — is mounted in the
transmission housing in contact with
the transmission fluid. It sends a
voltage signal to the PCM indicating the
temperature of the transmission.
VIN:
Vehicle Identification Number. This is
the factory-assigned vehicle serial
number. This number is stamped on a
number of locations throughout the
vehicle, but the most prominent
location is on top of the dashboard on
the driver's side, visible from outside
the car. The VIN includes information
about the car, including where it was
built, body and engine codes, options,
colors, and a sequential build number.
The VIN can also tell you what adapters