Actron Ford Code Scanner CP9015 - Manual (Page 64)

64
TFI-IV
Thick Film Ignition system,
version 4. An ignition
system consisting of a
distributor, ignition coil and
TFI-IV module. The ECA
controls the spark advance
timing. A camshaft position
sensor in the distributor
sends a reference signal
(called PIP) to the ECA.
The ECA sends a spark
advance signal (called
SPOUT) to the TFI-IV
module which fires the
spark coil. The distributor
mechanically switches the
spark voltage to the various
plugs in the usual manner.
The ECA determines
optimum spark timing from
sensor information – engine
speed and RPM, throttle
position, coolant
temperature, engine load,
vehicle speed, gear lever
position and knock sensor
condition.
Thermactor Air
System
An emission control system
consisting of an air pump,
air flow control valves (TAB
& TAD) and a catalytic
converter. The converter
removes pollutants from the
exhaust stream. An air
pump brings outside air
(when needed) and sends
it either to the exhaust
manifold (“upstream”) or
directly into the converter
(“downstream”). The ECA
controls the air path for
best performance under
different engine operating
conditions. The air pump
always runs when the
engine runs. Usually the
incoming air is directed to
the converter. Air is kept
out during extended idling
(prevent converter
overheat) or during very
cold engine starting. Air
goes into the exhaust
manifold during normal
engine warm-up. This helps
burn hot, unused fuel
vapors in the exhaust
stream (reduces pollutants
– speeds exhaust warm-
up). The TAB and TAD
valves may be separate
units, or combined into one
assembly.
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.
THS 3/2 and
THS 4/3
Transmission Hydraulic
Switch. These are pressure
switches used in some
automatic transaxles. They
send gear information to
the ECA as follows: THS 3/
2 (only) signal means 2nd
gear. Both THS 3/2 and
THS 4/3 signals means 3rd
gear. THS 4/3 (only) signal
means 4th gear.
TK
Throttle Kicker solenoid.
The ECA uses this solenoid
to apply vacuum (and thus
activate) the throttle kicker
actuator. The actuator
increases the amount of
idle position throttle
opening by a fixed amount.
The
ECA activates TK when
operating conditions require
faster idle, such as when
the A/C compressor is on,
or during cold engine
start-up.
TOT
Transmission Oil
Temperature sensor. This
sensor is a thermistor – a
resistor whose resistance
decreases with temp-
erature. It lies within the
transmission housing in
contact with the oil. The
ECA uses this sensor to
monitor transmission
operating temperature.
TP
Throttle Position sensor.
This is a rotary type
potentiometer connected to
the throttle shaft. It has a
voltage signal output which
increases as the the throttle
is opened. The ECA uses
this sensor to determine if
the engine is in idle, part
throttle or wide-open-
throttle operation. Then the
ECA can properly control
systems such as idle
speed, spark advance, fuel
delivery and emission
controls.
TTS
Transmission Temperature
Switch. Sends a
temperature status signal
to the ECA.
Vacuum Switch
A vacuum operated
electrical switch. The
switching action occurs
when applied vacuum
reaches a certain level. The
switches may either be
normally closed or normally
open. These are used
mainly in the MCU engine
control system. The
switches send signals to
the MCU module.
VAF
Vane Air Flow sensor.
This sensor is a rotary type
potentiometer connected to
a moveable flap. It is
located inside the vane
meter assembly – a
housing between the air
cleaner and throttle body
through which all incoming
air passes. Flowing air
pushes against the flap.
The sensor sends a signal
based on the flap position.
The voltage signal
increases when the flap
moves because of
increased incoming air
flow. The ECA determines
the amount of incoming air
with this sensor. This
information is used for for
control of fuel delivery,
spark advance and EGR
flow.
VAT
Vane Air Temperature
sensor. This sensor is a
thermistor – a resistor
whose resistance
decreases with
temperature. It is located
inside the vane meter
assembly – a housing
between the air cleaner
and throttle body through
which all incoming air
passes. The ECA
measures incoming air
temperature with this
sensor. This information is
used for fuel delivery
calculations.