Fiat 1996 Brava Service Manual page 598

Bravo-Brava iQty
98 range
JTD
Auxiliary units
Additional heater
50.
INTRODUCTION'
The heating inside the vehicle via the heater unit is insufficient, w i t h the engine cold, especially in the
case of diesel engines which reach operating temperature more slowly.
An additional heating system is offered for these engines which is activated when the engine is first run­
ning until a certain temperature is reached.
The system consists of an additional heating device, located on the engine coolant supply pipe to the
heater unit.
This device contains three spark plugs which are very similar to those used for pre-heating the combus­
tion chamber.
Location of car interior coolant heater
plugs
The additional heater containing the three heater plugs is located on the coolant supply pipe to the
heater unit.
The coolant temperature sensor is located on the same pipe, immediately upstream towards the engine
thermostat.
The three relays are connected by the diesel filter, on a special bracket fixed to the engine compartment
bulkhead.
The system control unit is located under the dashboard, behind the glove compartment.
Operating logic
The operation of the heater plugs is controlled by an electronic control unit which operates one, t w o or
three heater plugs thereby giving a supply 200W, 400W or 600W
This control logic depends on:
- the temperature of the coolant leaving the engine;
- the power level available;
- the engine speed.
The first information is supplied by a special temperature sensor located on the supply pipe towards the
heater; the control logic deactivates the heater plugs when the temperature of the coolant coming from
the engine exceeds 70 °C.
The control unit also takes into account the parameter of the temperature of the air in the engine com­
partment; it is not measured by a special sensor, but is assumed to be the same as the temperature of the
coolant during starting; the switching off figure decreases from 70 °C to 65 °C if the temperature of the
air is assumed to be greater.
Copyright by Fiat Auto XI-98 - Update
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