Fiat Bravo Service Manual page 129

Bravo-Brava fflw Engine
Fuel system
10.
P4A27AJ01
The signal therefore assumes a value close to 0 Volt when the throttle is completely closed, and a value
close to 5 Volt for an opening of 24° in relation to rest position.
The throttle opening range from 0° - 24° corresponds to tend reference points in the ECU map (a).
These represent the ten main positions taken up by the throttle valve, m this way, the ECU may recog­
nise small angular changes in the order of 2°25'.
This high degree of sensitivity allows the ECU to select base pulse constant from the specific maps with
greater precision under critical engine service conditions, i.e. when idling and under partial load.
From 18° of throttle opening up to full opening (about 90°), a signal is produced by terminal 4 of poten­
tiometer (B), i.e. terminal of second race (D).
This signal is sent to terminal 10 of the ECU and relates to engine service conditions at medium and full
loads.
The field of the second race is divided into ECU maps a with lower resolution than the first race, i.e. into
5 points corresponding to angular throttle changes of about 13°. The entire opening range of the throttle
valve therefore corresponds to 15 significant points or openings (alpha). These are identified by the
ECU by means of two potentiometer races.
With throttle valve opening angles between 18° and 24°, both voltage signals present simultaneously at
terminals 2 and 4, first and second race respectively, should respect a certain ratio.
Under the above conditions, the ECU runs a plausibility check to test signals from the first race (C - min­
imum/partial load) are perfectly synchronised with those of the second (D - medium/full load).
Terminal 1 of the potentiometer is earthed through terminal 11 of the ECU.
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