CRUISE CONTROL WITH ELECTRIC ACTUATOR
The electric actuator type cruise control system was intro-
duced on the BMW 733i and 528e models in 1982. From 1983 all
six-cylinder models will use this type.
The system is designed to operate at between 20 and approximately
90 mph. An electronic control unit (E.C.U.) controls an
electric actuator which maintains the desired road speed via
the throttle linkage.
Driver control is through a three-function switch operated by
a lever mounted on the right side of the steering column be-
hind the wiper lever.
Pushing the lever forward in the CONST position engages the
system and the car will accelerate until the lever is re-
leased. The E.C.U. contains a memory circuit which will hold
the speed that exists when the lever is released from the
CONST. position. Momentary operation of the lever in the CONST.
position will also cause engagement and lock the prevailing
speed into the memory.
Cruise control may be disengaged in any of five different
ways; momentarily moving the control switch up or down to OFF,
applying the foot brake, shifting the automatic transmission to
neutral, depressing the clutch, or whenever the actual speed
drops more than 15 mph below the memory speed.
Following disengagement, the car can be returned to the pre-
viously selected speed by pulling the control lever to RESUME.
The memory circuits in the E.C.U. are reset whenever the
lever is moved to CONST, but the only time the memory is cleared
is when ignition is turned off.
The E.C.U. receives a processed signal from the electronic
speedometer, which is equivalent to actual road speed. Con-
sequently, speedometer problems will affect cruise control.
