turn signal BMW 5 SERIES 1981 E28 Cruise Control With Electric Acutator

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.