Cruise Control: Description and Operation
Design and functionThe different sensors feed input signals to the control module microcomputer, which decides on the value and status of the input signals. After approving these, a relay in the control module is connected and feeds voltage to the vacuum pump and regulator. For continued use, the control module monitors and operates the system for optimal function.
The system is in two main parts.
Engaging cruise control
The switch must be in the ON position, the speed must exceed 35 km/h (22 mph) and no reason for disengagement exists.
When pressing the SET button on the selector switch, the current vehicle speed is programmed in the control module memory. There it will remain until the next time the SET button is pressed or the ignition is turned off.
If the RESUME button is pressed after disengaging, the control module will set the system to the speed recorded in the memory, provided a speed has been entered.
Disengaging cruise control
The cruise control is always disengaged by breaking the current to the relay in the control module which feeds the vacuum pump and regulator. Simultaneously, the ground connections of the vacuum pump and regulator are broken so that regulation of the system ceases.
Disengaging:
- Selector is set to OFF
- Speed drops below 35 km/h (22mph)
- Brake or clutch pedal is depressed, when a control circuit is energised via the pedal valve contact
- The brake pedal is depressed, when an- other control circuit is energised via the brake light switch
- Start inhibitor switch on cars with automatic transmission. In the P or N positions the start inhibitor switch closes, thus disengaging the cruise control system
- Safety disengaging.
Taken care of by the control module in the event of rapid acceleration (wheel-spin) and strong retardation (wheel-lock after wheelspin). Disengaging also occurs when the engine cannot maintain set speed, climbing a steep incline (less than 75% of set speed)