Fiat Bravo Service Manual page 134

Engine Bravo-Brava © ^
Fuel system
10.
Intake air temperature sensor
Intake air temperature is measured by temperature sensor (B) located on the butterfly valve case.
This sensor consists of a plastic case on which is located the reactive element (1), which consists of a
resistance (N.T.C.) that varies in inverse proportion to temperature.
If temperature is between 15° C - 30° C, resistance is 3.3 -1.5 kQ. If temperature is about 80° C, the re­
sistance is 0.280 - 0.360 Q.
Terminal 13 of the ECU (A) supplies terminal 1 of sensor (B); the circuit is earthed from terminal 2 of the
sensor to terminal 27 of the ECU.
When the sensor is disconnected, the ECU supplies a voltage of 5 V. With the sensor connected, the
supply voltage alters according to temperature (internal sensor resistance).
Recovery
When the air temperature sensor is short-circuited (d.c.) or circuitis open (a.a), the ECU receives im­
plausible signals, i.e.:
- d.c. sensor: air temperature > 128° C
- a.c. sensor: air temperature < -50° C
In these cases, the ECU implements a Recovery strategy which takes an air temperature of 20° C as a ref­
erence.
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Publication no. 506.670