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B
TFP:
Transmission Fluid Pressure
TFT:
Transmission Fluid Temperature (Sensor)
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. Potentiometer-type sensor connected to the throttle shaft. Its
voltage signal output increases as the throttle is opened. The PCM uses this signal to
control many systems such as idle speed, spark advance, fuel delivery, etc.
TTS:
Transmission Temperature Sensor. A resistance sensor mounted in the transmission
housing in contact with the transmission fluid. It sends a voltage signal to the PCM indi-
cating the temperature of the transmission.
VECI:
Vehicle Emission Control Information. A decal located in the engine compartment
containing information about the emission control systems found on the vehicle. The
VECI is the authoritative source for determining whether a vehicle is OBD II compliant.
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 prom-
inent 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, and a sequential build number.
VSS:
Vehicle Speed Sensor. Sends a frequency signal to the PCM. The frequency increases
as the vehicle moves faster to give the PCM vehicle speed information used to determine
shift points, engine load, and cruise control functions.
VTD:
Vehicle Theft Deterrent
WOT:
Wide-Open Throttle. The vehicle operating condition brought about when the throttle is
completely (or nearly) open. The PCM will typically deliver extra fuel to the engine and
de-energize the A/C compressor at this time for acceleration purposes. The PCM uses
a switch or the Throttle Position Sensor to identify the WOT condition.