850 T-5R L5-2.3L Turbo VIN 58 B5234T5 (1995)
Cruise Control Module: Description and Operation
Control module
This contains the "brain" of the system which is a micro-computer. It registers the speed when the SET button is pressed. It responds by charging the
vacuum motor, through a relay, which regulates the pressure in the vacuum servo and thus the speed of the vehicle.
The set speed is stored in the memory of the control module either until the system is switched off by moving the switch on the direction indicator
stalk to OFF or the SET+ or- button is pressed to change the speed stored in the memory.
The control module has several safety functions to prevent malfunction in the event of a fault developing in the system. The speed must exceed 35
km/h (22 mph), the control module must be set to ON and its SET button must be pressed for the control module to work and for its relay to start the
vacuum pump. If the car is equipped with automatic transmission the control module is de-activated in the P and N positions.
The micro-computer monitors and disengages if there is abnormal acceleration (for example wheelspin) or deceleration (for example wheel- lock). It
also disengages if the speed drops below 75% of the set speed, which can occur on a steep uphill climb, when the engine cannot maintain a constant
speed.
Another important function for the control module is to store faults in the form of codes and handle the diagnostic unit which makes it possible to fault
trace the system.
