Operation logic

(Continued)

OPERATION LOGIC

SYSTEM SELF-ADJUSTMENT

The ECU is equipped with a self-adjusting function with the purpose of acknowledging changes due to time and ageing in the engine and in its components.

These changes are saved in the ECU memory as modifications to the basic map. The purpose is to adjust the system operation to the progressive alterations of the engine and the engine components with respect to new units.

The self-adjustment function also compensates for the inevitable diversity between spare parts (due to manufacturing tolerance rates) which may be changed in time.

The ECU changes the basic exhaust gas analysis map with respect to new engines.

187B10T03A

SELF-TEST

The ECU self-test system runs the following self-test strategies thanks to a permanent memory.

Sensor and actuator test:

• rev and TDC sensor
• absolute pressure sensor
• coolant temperature sensor
• intake air temperature sensor
• throttle position potentiometer
• faulty actuator control port
• idling actuator
• injector
• ignition coils

Fault and error test:

• failed ECU synchronisation on phonic wheel during research and when the engine is running
• AC or DC lambda sensor
• combinations of several faults in the same sensor

The ECU replaces the signal from the faulty sensor/actuator with pre-programmed recovery data to ensure engine operation.

Only the signal from the rev and TDC sensor cannot be replaced with recovery data.

The fault is stored permanently in the system memory. The faulty sensor is excluded from the system as long as the signal it transmits does not become coherent.

Fault detection and replacement with recovery data lights up a warning light on the instrument panel.

The warning light comes off in the following cases:

• faulty sensor/actuator is replaced
• fault is temporary.

In this case, the ECU stores data regarding the fault in memory.

187B10T04A

FIAT CODE ACKNOWLEDGEMENT

When the ECU receives a signal indicating the ignition key is turned to "MAR", it dialogues with the FIAT CODE ECU and enables engine ignition.

(Cont.)