Autodiagnosis

Autodiagnosis

The injection/ignition system is equipped with an "autodiagnostic" function which memorizes any faults at the sensors and actuators, making it easier to identify and correct them.

If a fault is detected at the sensors, the electronic control unit replaces the information coming from the faulty sensor with information stored in the memory (recovery) to allow the operation of the engine. The detection of a fault involves it being permanently memorized and the sensor excluded from the system until the signal is compatible once again.

The same procedure is applied if the fault involves an actuator or its controls. The detection of a fault and the replacement with recovery data involves the failure being signalled by means of the specific warning light in the instrument panel coming on.

The warning light comes on each time the ignition key is turned to the ON position and, if there are no faults, the warning light goes out after 4 seconds.

Fault diagnosis using the SDC or Examiner

This system temporarily stores any faults which have taken place inside the control unit memory and, when the ignition is switched off, it transfers them to the permanent memory to allow them to be read with the diagnostic equipment (SDC or Examiner).

There is a diagnostic socket on the left hand side of the engine compartment for connection with the diagnostic equipment.

The exchange of data takes place by means of two diagnostic lines K and L; line K is used for transferring data from the control unit to the diagnostic equipment and line L is used for transferring data from the diagnostic equipment to the electronic control unit.

The exchange of data between the control unit and the diagnostic equipment takes place in accordance with standard ISO 4 communication protocol; the information is coded and transmitted NRZ (Non Return Zero), with a positive logic and at a speed of 7812. 5 Baud.