# Cruise control operation

The cruise control will not operate below speeds of 45 km/h (28mph). The speed is regulated via the control unit which stores the selected speed and compensates with throttle control to keep actual speed as close as possible to selected speed. Variation is approximately 2 km/h.

The cruise system will shut off if actual speed drops by approximately 15 % from selected speed. While this may seem a strange thing, if not impossible, for a correctly functioning system to do, if the car is excessively loaded, perhaps towing a trailer, and trying to pull up a hill, it is possible for the cruise to create an overload situation, causing derivability problems. To prevent this, the cruise will shut off, forcing the driver to downshift to alleviate load.

If the road speed increases above the selected speed by approximately 6 to 8 km/h , a quick action clutch in the cruise motor will disengage the throttle , allowing it to return to idle, until the actual speed comes back down to the selected speed.

Vehicles built prior to 9/87 use the following control movements :

| Pushing the lever forward, towards the dash, for a short time, stores the current vehicle speed in the cruise memory and the car will maintain that speed. Holding the lever forward will accelerate the vehicle and the system will store the speed when the lever is released.
| Pulling the lever backwards, towards the driver will bring the vehicle speed to the previously stored speed. Use this feature after braking.
| Moving the lever either up or down will shut off the cruise, but the system will retain the final selected speed in memory until the ignition is shut off.
| Stepping on the brake or clutch pedals, or moving the automatic shifter will cancel the cruise control.

As of 9/87 production several changes were made to the cruise system :

| Pulling the lever toward the steering wheel will set the current speed in memory. Holding the lever in this position will cause the car to decelerate.
| Pushing the lever towards the dash will set the current speed in memory. Holding the lever in this position will cause the car to accelerate.
| In both the above instances, tapping the lever quickly in the desired direction will decrease, or increase, the set speed by 1 km/h (0.7 mph) increments
| Moving the lever upward will resume the last stored speed.
| Moving the lever down will shut off the cruise control.
| Stepping on the brake or clutch pedals, or moving the automatic shifter will cancel the cruise operation.

E30 M3 Repair Manual V2.7. Copyright ©1999-2001 Koala Motorsport & Brett Anderson