Maintenance Manual for J2 Sedan
Electronic Control System
of Engine
179
Section III Structural Principle and Inspection of Engine Electronic Components
I.
Intake Manifold Absolute Pressure (MAP/MAT) Sensor
1. Description
1) Intake absolute pressure sensor (MAP) is a pressure sensitive variable resistor. Diaphragm inside of
sensor is connected with a magnet core placed through the coil. When intake pipe pressure changes,
the diaphragm will drive the core to movement and thus change output voltage of sensor .With
sensor output voltage, ECU can determine engine intake volume, with which and reference to other
signals, injection volume control is achieved. .MAP sensor is also used to measure atmospheric
pressure during starting; under certain conditions, it allows the ECM to be adjusted automatically at
different altitudes. ECM provides 5V voltage to MAP sensor and receives voltage signal by the
signal line. The sensor is grounded with a wire from its variable resistor. MAP sensor input signal
affects ECM fuel output and ignition timing control.
2) Intake temperature sensor element is a thermistor with negative temperature coefficient (NTC). Its
resistance increases with the intake air temperature decreases. Engine ECU detects intake air
temperature changes via a contrast circuit.
2. Installation Position
Installed on the back of throttle
3. Circuit Diagram
Pin 19: 5V voltage signal
Pin 59: Manifold pressure sensor signal
Pin 40: Power ground
Pin 25: Intake air temperature sensor signal
Operating voltage: 5 ± 0.1V
Fig. 4.3.001
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5V power supply 1
Sensor grounding
