Rain/Light Sensor (RLS)

Rain/light sensor (RLS)
The (E85) Z4 is available with a rain/light sensor (RLS) as an option. The headlights are switched on/off automatically by the rain/light sensor according to the ambient light conditions. There are two additional optical sensors for the RLS integrated in the casing of the automatic interval control (AIC) module. The two new sensors supplement the otherwise unchanged wiper interval control function as follows:
^ An ambient-light sensor detects the light intensity above the vehicle within a wide scanning angle.
^ A forward light sensor detects the light intensity within a narrow scanning angle directly ahead of the vehicle.
An internal processor calculates from the readings taken by the sensors whether the preconditions for switching on the lights are present. The following conditions are checked for:
^ Twilight
^ Complete darkness
^ Entry in underground car park
^ Entry in tunnel
^ Precipitation such as rain or snow

Note: If the wiper switch is set to intermittent wipe, the precondition for switching on the lights is detected once the wiper frequency exceeds a predefined level (factory setting is 15 wiper cycles per minute). If the wiper switch is set to Speed I or 11, the precondition for switching on the lights is constantly satisfied.

If any of the above conditions is met, the RLS on the (E85) Z4 sends the information to the light switch centre.
In order to be able to control the headlights automatically, the RLS must be activated by a separate light switch setting on the light switch centre.
In addition, the lights are switched on if any of the following faults occur:
^ The RLS detects a sensor fault.
^ There is a fault in communication between the RLS and the light switch centre.
The following lights are controlled by the light switch centre:
^ If terminal R is ON, the side lights, the number plate light and the instrument panel lights are switched on.
^ If terminal 15 is ON, the side lights, the dipped headlights, the number plate light and the instrument panel lights are switched on. If only the side lights are required at that setting, the switch on the light switch centre must be manually set to Side lights "ON."
^ When the ignition switch is at position 0,the exterior/instrument panel lights are switched off.
The sensitivity of the RLS can be set by means of the Car Memory function.

Safety note: Automatic control of the headlights is not a substitute for individual assessment of the light/visibility conditions (e.g. fog) by the driver. In order to avoid safety risks in such situations, the lights must be switched on manually by the driver.