steering BMW 5 SERIES 1985 E28 Cruise Control

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.

CRUISE CONTROL

The BMW cruise control is designed to operate between 20

and approximately 90 mph. An electronic control unit (E.C.U.)

controls a vacuum operated servo unit which actuates the

throttle linkage to maintain the required road speed.

Drive control is through a three function switch operated

by a lever mounted on the right side of the steering column

behind the wiper lever.

Pushing the lever forward in the CONST position engages the

system and the car will accelerate until the lever is

released. 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 transmission to

neutral, or whenever the actual speed drops more than 7 mph

below the memory speed.

Following disengagement, the car can be returned to the

previously 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.