Management Of The Engine Starting Block Function (Fiat Code); Management Of Radiator Fan; Knock Control - Fiat Bravo Service Manual

Engine
Fuel system
10.

Knock control

The purpose of this strategy is to detect the presence of knocking, by processing the signal coming from
the relevant sensor. The strategy continuously compares the signal coming from the sensor w i t h a thres-
hold, w h i c h in turn is constantly updated to take account of background noise and ageing of the engine.
If the system recognizes the presence of knocking, the strategy reduces the ignition advance until the
phenomenon disappears. The advance is then gradually restored to the basic value or until the phe-
nomenon arises again. In particular, increases in advance are made gradually, while decreases are made
immediately.
Under conditions of acceleration, the strategy uses a higher threshold, to take account of the increased
noise of the engine in this condition.
The strategy also has a self-adaptive function which memorizes, in a non-permanent manner, decreases
in advance that are repeated continuously, so as to adjust the advance to the different conditions of the
engine (e.g. use of low octane number fuel). The strategy can restore the advance to the threshold value
stored in memory when the conditions that gave rise to the decrease in advance disappear.
MANAGEMENT OF T H E ENGINE S T A R T I N G B L O C K F U N C T I O N (FIAT C O D E )
The system has an engine starting block function. This function is carried out by a specific control unit
(Fiat CODE), which can dialogue w i t h the fuel injection-ignition control unit, and an electronic key,
which has a special transmitter for sending a recognition code.
Whenever the ignition is switched off, the Fiat CODE system completely disables the fuel injection-igni-
tion control unit.
When the ignition is switched on, the following operations take place:
1 - the fuel injection control unit (whose memory contains a secret code) sends a request to the Fiat
CODE control unit to send the secret code to disable the function block;
2 - the Fiat CODE control unit responds by sending the secret code only after first receiving the recogni-
tion code transmitted by the ignition key;
3 - recognition of the secret code permits the disablement of the block on the fuel injection-ignition
electronic control unit and the normal operation of the latter.
NOTE Because of the presence of the Fiat CODE system, during fault diagnosis and/or operating
checks, DO N O T C A R R Y O U T tests using another fuel injection-ignition
do, the Fiat CODE control unit would transfer the (unknown) recognition code to the test con-
trol unit, which would then be unusable on other vehicles.

MANAGEMENT OF RADIATOR FAN

The control unit checks the operation of the radiator fan directly, in accordance w i t h the engine coolant
temperature and whether the climate control system is switched on.
The fan comes on when the temperature exceeds 97 °C (1 st speed) and 102 °C (2nd speed). It is swit-
ched off w i t h a hysteresis of 3 °C below the threshold for switching on.
The high and low speed functions are managed by the intervention of specific relays located in the con-
trol unit of the climate control system, and controlled by the control unit.
1 2
Bravo-Brava
'98 range
control unit. If you
Publication no. 506.670/14
ft