Self-diagnosis

performance is requested (high acce-
laration), the control unit momentarily
interrupts (7-10 seconds) the supply
to the compressor.

• Connection with the ALFA ROMEO
  CODEx as soon as the Motronic con-trol unit receives the signal that the
  key has been switched to "MARCIA",
  it "asks" the ALFA ROMEO CODE
  system consent to start the engine;
  this consent is only given if the ALFA
  ROMEO CODE control unit recog-nises the code of the key engaged in
  the ignition switch as correct. The dia-logue between the two control unit
  takes place on diagnosis line K al-ready used for the Alfa Romeo Tester.

NOTE:
Starting from chassis no. ... the version
of the electronic ignition/injection control
unit with updated software is adopted.
This control unit is distinguished by a
yellow dot, it possesses new, more ef-ficient maps which are the result of ever
increasing experience owing to the use
on this vehicle.

• It also has - for T.SPARK versions only
  - a special connection with the ignition
  switch for detecting STARTING: sig-nal at pin 65 of the control unit; this
  makes it possible to avoid possible
  inconveniences to the engine when it
  is started, suitably optimising the par-ameters controlled by the system.

SELF-DIAGNOSIS

The control unit is equipped with a self-diagnosis system which continually checks the signals coming from the various sensors and compares them with the permitted limits. If these limits are exceeded, the system recognises a malfunction and replaces the anomalous values with suitable average values so that the vehicle is able to proceed

safety, though not under optimum condi-tions, to a point where Network assist-ance can be gained: this method has been termed the "limp home" capability. The parameters which can be "sub-stituted" by the control unit in the event of a malfunction are: air-flow meter, idle adjustment actuator, engine tempera-ture sensor, throttle valve sensor and vapour recovery solenoid valve. If a malfunction occurs in the control unit, or to the r.p.m. and timing sensor or injectors, the system will not identify the fault and the vehicle will come to a halt. The self-diagnosis system also enables an efficient and rapid identification of the anomalies to be made when connected to the ALFA ROMEO Tester (refer to specific publications)

Troubleshooting is however possible even without the aid of this instrument by following the instructions given below in this section (see "Troubleshooting").

COMPONENTS

The electronic control unit (S11) re-ceives the signals from sensors which "read" the functioning of the engine. It then processes these signals on the basis of a logic system stored in "maps" which make an optimum correlation be-tween the various parameters and oper-ates the actuators so that the engine operates with the highest degree of per-formance and regularity.

The control sensors are the following:

• engine temperature sensor (S7);
• air flow meter (with incorporated air
  temperature sensor) (S5);
• throttle body sensor (S38);
• R.P.M. and timing sensor (S31);
• oxygen sensor (lambda probe) (S35)

The actuators controlling the system are:

• electroinjectors (S3).
• ignition coil (A8)
• double coil (ABa: ABb) with power mo-dule (N1a: N1b) in the T SPAFIK 1.8 and 2.0 models:
• fuel pump (P18);
• idle adjustment actuator (S29);
• timing variator (S15) -only for T.
  SPARK models;
• vapour recovery solenoid valve
  (M15).