3022534 - 5580A cruise control system

SPECIFICATIONS:

The figure shows the location of the Cruise Control.
1 - Cruise Control lever 2 - Lights/direction indicators lever 3 - Front/rear window wipers lever 4 - Air Bag clock spring 5 - Horn/radio controls cable

OPERATION

The engine managment systems for petrol engines with motorized throttles and diesel engines with electronically controlled injection times include the Cruise Control function, i.e. a system which automatically maintains the cruising speed set by the driver.
1 - Cruise Control lever 2 - 6-pin connector 3 - Resume button for recalling the memorised speed 4 - Ring switch for memorising increase/decrease (acceleration position: +; deceleration position: -) 5 - Ring swtich (ON: Cruise activated; OFF: Cruise deactivated) 6 - Injection control unit (ECN)The Cruise Control is integrated in the steering column switch unit which also controls the direction indicators and front/rear window wiper.

The third lever on the steering column switch incorporates the Cruise Control commands, namely:

  • a ring switch for activating/deactivating the system;
  • a ring switch which memorises the car's increase/decrease in speed;
  • a Resume button for recalling the memorised speed.
The electronic system is managed by the injection unit (ECN) ME7.3.1. It automatically maintains the cruising speed set by the user and actuates this control via a command on the motorised butterfly. - The Cruise Control system may be present on both cars with manual gearbox and cars with automatic transmission connected to the engine control on CAN network. Some signals may pass either through the CAN network or through discrete pins (i.e. via cables of the circuit), depending on the version.

MEMORISATION OF THE PRESELECTED SPEED

To activate the Cruise Control function, it is necessary to:

  • 1 activate the bistable ring switch in the ON position;
  • 2 bring the car up to the desired speed; remember that the Cruise Control can only be activated for speeds of over 30 km/h. It is advisable to switch it on in fourth gear or upwards, and on road conditions which allow the set speed to be maintained safely.
  • 3 operate the ring switch towards the (+) mark: this is switch with automatic return.
  • 4 release the accelerator pedal and allow the system to act directly;
  • 5 the instrument panel (NQS) will light up the light (LED) fixed in accordance with the signal coming from the fuel injection control unit (NCM), via the CAN network, indicating the Cruise Control operating status. When it goes out, this indicates the deactivation of the system.

VARIATION OF THE MEMORISED SPEED

To change the memorisation of the car speed corresponding to the moment when it was memorised, it is necessary to:

(A) Speed increase:

  • operate the ring switch towards the (+) mark: an acceleration ramp is produced at a constant gradient which can be programmed;
  • on release of the switch (automatic return of the switch), the system maintains and memorises the new speed reached by the car.

(B) Speed reduction

  • operate the ring switch towards the (-) mark: the car speed is reduced in relation to that set previously by the Cruise Control; release the button and the system will maintain the new speed reached by the car.
The Cruise Control can operate within the full range of rpm permitted by the engine, for both versions with automatic transmission on CAN network and versions with manual gearbox.

FUNCTION OF RESUME BUTTON

By pressing the automatic return button located on the top of the Cruise Control lever, this function enables the care to be brought to the last speed value memorised, if the Cruise Control has been switched off because of particular conditions (e.g. operation of the cluth or use of the stop switch during braking).In the case of manual gearbox, the same gear used when the speed is sest must have been engaged. If a speed value has not been recognised, pressing the button has no effect.

DEACTIVATION OF THE CRUISE CONTROL (BY THE USER/SUBSYSTEMS)

(A) The Cruise Control is deactivated by the user by:

  • turning the ring switch to the OFF position
  • switching off the engine;
  • operating the brake or clutch pedal (in these cases the last speed reached remains memorised, and can be recalled by pressing the Resume button).
  • vehicle speed below the permitted minimum (about 30 km/h) or above the permitted maximum;
  • setting the automatic transmission selector lever to position P, N, R (on robotised gearbox the information is on the CAN network); on manual gearboxes, if the lever is operated without using the clutch, the rpm and car speed will not be consistent; in all these cases, pressing the Resume button re-activates the system.
  • operating the accelerator with Cruise Control active: by pressing the accelerator (e.g. for overtaking) the Cruise Control permits a temporary increase in the car speed because it is temporarily deactivated, but as soon as the action on the accelerator pedal ceases, the system reactivates the memorised speed setting.
The Cruise Control cannot operate with manual gearbox in 1st gear or Reverse, and with automatic transmission is P, N, R (the lever position information is on the CAN network).
The recognition of the engaged gear with car moving for automatic transmission is available on the CAN network; for the manual gearbox, the engaged gear is recognised by comparing the car speed with the engine rpm with clutch engaged.For safety reasons, the ASR (Antislip Regulation) and VDC (Vehicle Dynamic Control) functions have priority over the Cruise Control; when the operation of the ASR/VDC is over, the Cruise Control is automatically reactivated at the last speed value memorised.

(B) The Cruise Control is automatically deactivated if:

  • acceleration higher than the set limit occurs (e.g. a rapid descent);
  • deceleration higher than the sest limit occurs: the gear selector lever is used without the clutch.

However, the system switches off automatically when the signals used by the Cruise software are incorrect because they are attributable to faults in the components;

  • vehicle speed sensor;
  • accelerator pedal potentiometer;
  • plausibility of brake/stop lights switches;
  • plausibility of clutch switch;
  • lever position on automatic transmissions;
  • plausibility of Cruise switch and Resume button;
  • plausibility of Cruise switch and (+) (-) buttons;

The Cruise Control system is also deactivated in all cases where errors occur on components which impair engine operation, such as:

  • engine management control unit;
  • engine rpm sensor;
  • electronic throttle body actuators/sensors (petrol engines);
  • engine load meter (petrol engines);
  • coils (petrol engines);
  • fuel injectors;
  • high-pressure system components (diesel engines);
  • turbo actuators/sensors (if present).
A 'fault' is a serious malfunction of the engine control system or Cruise Control system, such as to require that the Cruise Control become 'blocked' (i.e. disabled until the engine is turned off). An 'anomaly' is an anomalous condition (due to a malfunction or incorrect command from the user, such as, for example, involuntary simultaneous activation of the Resume buttons and (+) (-) ring buttons, such as to require that the Cruise Control be deactivated, but not blocked. In both cases of fault and anomaly, an error code which can be read by a diagnostic instrument must be memorised. Cruise Control errors must not cause the fuel injection control unit (ECN) warning light to come on, or the Cruise Control warning light.