Pre-Heating Control Unit - Fiat Bravo Service Manual

Engine
Fuel system
10.
24

Pre-heating control unit

The operation of the heater plugs takes place
via the pre-heating control unit, under the d i -
rect control of the electronic control unit.
There is an "intelligent" relay inside w h i c h
sends a return response (feed-back) to the
injection control unit w h i c h is informed in
this way of any failures of the pre-heating
control unit or short circuit to earth of the
heater plugs.
The diagram shows the connectors on the
pre-heating control unit base and the rele-
vant pin-out.
Connections
1. Vehicle earth
2. Not connected
3. Ignition switch ( + 1 5 )
4. Electronic control unit (pre-post heating
5. Electronic control unit (fault diagnosis)
8. Battery positive
9. Heater plugs
10. Heater plugs
Air temperature sensor
The intake air temperature sensor is, on this
version, separate from the air flow meter: it
comprises a standard NTC (Negative Tem-
perature Coefficient) where the electrical re-
sistance decreases as the temperature in-
creases.
Since the control unit intake circuit is de-
signed as a voltage divider, this voltage is d i -
vided between a resistance in the control unit
and the sensor NTC resistance.
As a result the control unit is capable of eval-
uating the variations in the sensor resistance
through the changes in voltage and thereby
obtain information concerning the tempera-
ture.
P4A24EJ02
IX-96 - Update
Bravo-Brava
activation)
ft
TD100
Print no. 506.670/08