Location Of Preheating Components In Car; Preheating Electronic Control Unit; Introduction - Fiat Brava Service Manual

Electrical system
Preheating control system
55.
INTRODUCTION
The preheating control system brings the temperature of the prechambers up to a temperature to permit
self-ignition, and it consists of the following components:
- a preheating electronic control unit located in the engine compartment;
- four rapid glow plugs;
- a wait-to-start warning light located on the instrument panel.
Location of preheating components in car
P4A155L01
1. Fuel filter 4. Preheating control unit
2. Fuel outlet 5. Glow plugs
3. Fuel inlet 6. Manual device for injection advance when cold
PREHEATING ELECTRONIC CONTROL UNIT
The purpose of the electronic control unit in the engine compartment is to carry out the following:
- deliver current from the battery to the spark plugs for a length of time varying in accordance with the
engine compartment temperature, before starting. This temperature is recorded by a negative tempera­
ture coefficient (NTC) gauge located in the electronic control unit;
- keep the wait-to-start warning light on for a period of time depending on the engine compartment
temperature (from 1.5 to 4.5 seconds at a temperature of 70°C, from 20 to 27 seconds at a temperature
of -20°C);
- ensure for a so-called "distraction" time (about 20 seconds) that the glow plugs remain supplied if the
engine does not start, and if the engine does start, to interrupt the delivery of current at the end of the
distraction time;
- if one of the glow plugs or the current cable accidentally shorts to earth, immediately stop the delivery
of current.
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