C - electric/electronic circuit

The ECU controls pin movements through 4 electrical lines and memorises the positions taken up. Reference position 0 is achieved when the actuator pin is fully extended and no supplementary air flow is present.

When the engine is off, the ECU positions the actuator pin in accordance with a value recorded in the memory so it is ready for the subsequent start-up stage.

While the engine is idling, optimal air control motor position is computed by the ECU on the basis of coolant temperature and any external loads.

The ECU also monitors battery terminal voltage continually. If for any reason terminal voltage is <9 Volt, or >17 Volt, the ECU will not allow the air control motor to move because efficient operation cannot be assured under these conditions.

The cross section shows all components of the step motor, namely:

1. a) Plunger or plunger pin
2. b) Rotor assembly
3. c) Insulating layer
4. d) Magnetic core
5. e) Worm screw
6. f) Bearing seat
7. g) Ball bearing
8. h) Electrical connector
9. i) Rotor sleeve
10. l) Stator assembly made up of: winding, polar expansions and coil
11. m) Outer case
12. n) O-ring
13. o) Compression spring
14. p) Plunger guide support

C - ELECTRIC/ELECTRONIC CIRCUIT

Connects all injection/ignition system components and provides them with electricity. It consists mainly of an ECU and the following components.

• Two system supply relays
• Throttle valve position sensor
• Coolant temperature sensor
• Fuel pump submerged in tank
• Four injectors
• Absolute pressure sensor
• Intake air temperature sensor
• Engine idle speed regulation actuator (step motor)
• Rpm and TDC sensor
• Ignition coil with four high tension outlets and power module incorporated
• Lambda probe
• Fuel vapour control solenoid
• Four spark plugs
• Inertia safety switch
• Diagnostic socket for Fiat/Lancia Tester
• Injection-ignition system failure warning light