Isuzu 2008MY N Series Workshop Manual page 387

1A-384 Engine Control System (4HK1)
The FT sensor is installed to the fuel supply pump. The
FT sensor is a variable resistor and it measures the
temperature of the fuel entering the fuel supply pump.
When the FT sensor is cold, the sensor resistance is
high. When the fuel temperature increases, the sensor
resistance decreases. With high sensor resistance, the
ECM detects a high voltage on the signal circuit. With
lower sensor resistance, the ECM detects a lower
voltage on the signal circuit.
Intake Air Temperature (IAT) Sensor
Euro 4 Specification
Except Euro 4 Specification
The IAT sensor is fitted between the air cleaner and
turbocharger. It is internal to the mass air flow (MAF)
sensor (Euro 4 specification). The IAT sensor is a
variable resistor and it measures the temperature of the
air entering the engine. When the IAT sensor is cold,
the sensor resistance is high. When the air temperature
increases, the sensor resistance decreases. With high
sensor resistance, the ECM detects a high voltage on
the signal circuit. With lower sensor resistance, the
ECM detects a lower voltage on the signal circuit.
Mass Air Flow (MAF) Sensor
))9"$-50 "
The MAF sensor is an air flow meter that measures the
amount of air that enters the engine. It is fitted between
the air cleaner and turbocharger. A small quantity of air
that enters the engine indicates deceleration or idle
speed. A large quantity of air that enters the engine
indicates acceleration or a high load condition. The
MAF sensor assembly consists of a MAF sensor
element and an intake air temperature (IAT) sensor that
are both exposed to the air flow to be measured. The
MAF sensor element measures the partial air mass
through a measurement duct on the sensor housing.
MFW4ADSH003301
))9"$-50 "