Fiat 1998 Marea Weekend, Руководство по обслуживанию

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Engine
Marea-Marea
Weekend @>
Fuel system
1998 range
10.
FAULT DIAGNOSIS
Full fault diagnosis can be carried out on the injection-ignition system through active dialogue with an
Examiner or SDC station.
If the sensors are found to be faulty, the electronic control unit replaces the faulty data output with a
stored signal (recovery) so that the engine can continue to operate.
When a fault is detected, it is stored permanently and the sensor is cut off from the system until the signal
is again compatible.
The same procedure is applied if the fault affects an actuator or actuator control port. When a fault is de-
tected and replaced with a recovery value, the fault is indicated by means of a warning light on the in-
strument panel.
The following devices may be managed using the electronic control unit recovery system:
- Idle speed actuator - Coolant temperature sensor
- Ignition coils - Knock sensor
- Fuel vapour recirculation solenoid - Throttle position sensor
- Pressure and air temperature sensor - Lambda probe
In the case of control unit or rpm sensor faults, the system detects the fault but cannot replace it with a
recovery value and the vehicle stalls. Anomalies may be detected in the control unit memory using an
Examiner or SDC station.
Error recognition and storage
An error is detected by means of a validation system, which works as follows:
When an error is detected, it is monitored for a time to rule out the possibilty of interference on the tester
line. Once this stage is over, the error is considered to be present and stored in the RAM memory (filtered
error). A check is then carried to ensure the error continues to be present for a further period of time.
Once this stage is over, the error is stored permanently (validated error) and the fault warning light
comes on. The error is written into the EEPROM memory after the ignition key has been turned back to
STOP.
Error frequency counter
A frequency counter is allocated to each error. This is used to determine the moment at which a fault
which is no longer present was first stored. The first time a validated error is recorded, the counter is set
at a fixed calibration value.
The counter is decreased whenever the vehicle is started up without the fault reappearing. If the counter
goes down to zero, the fault is automatically deleted from the EEPROM memory.
Error deletion
Errors may be deleted from the EEPROM memory in one of two ways:
- using a tester device (Examiner or SDC station), in active test mode
- by zeroing the error frequency counter.
NOTE Data recorded in the EEPROM memory are not deleted when the control unit is disconnected
from the system, even for long periods.
System fault warning light management
The control unit turns on the warning light to check it is working and keeps it on for 4 seconds whenever
the ignition key is turned to MAR. The warning light is also lit whenever a validated error occurs - i.e. as
long as the fault persists - and is turned off when the fault disappears.
62 Publication no. 506.763/09