900 Turbo Convertible L4-1985cc 2.0L DOHC Turbo EFI (1994)
Intake Air Temperature (IAT) Sensor: Description and Operation
The temperature sensor is located in the intake manifold in front of the throttle and is of the NTC type. The Engine Control Module (ECM) measures the
air temperature in the intake manifold by supplying the sensor with 5 V through a 2.74 kOhm resistor built into the ECM from pin 46. The sensor is
grounded from pin 67. The voltage across the resistor in the ECM is proportional to the intake air temperature.
The value is used together with the pressure in the intake manifold to determine the density of the air drawn in and consequently the engine load. The
fuel injection time is proportional to the engine load.
If the sensor does not work or if there is an open circuit, the ECM sets a substitute temperature of 8°C and the malfunction indicator lamp in the main
instrument lights up.
