Rain/Driving-Light Sensor (RLS)

The new RLS replaces the familiar Rain Sensor already in use. The RLS now has the added functions of monitoring ambient light conditions to influence the operation of the headlights.

The driving lights (headlights) are turned on and off automatically based on input from the RLS depending upon ambient light conditions.

Fig 1: Rain/Driving-Light Sensor (RLS)

Courtesy of BMW OF NORTH AMERICA, INC.

The new RLS contains two additional optical sensors have been integrated in the sensor housing. The RLS continues to use similar rain sensing electronics as used on the previous AIC system. The two additional light sensors are used for headlight operation.

The two sensors have the following function:

Sensor number 1 is a surrounding-light sensor that records the light intensity in a wide angle above the vehicle.
Sensor number 2 is a frontal-light sensor that records the light intensity in a narrow angle in front of the vehicle. A processor measures and determines which sensor is switched on.

The following conditions are monitored by the (RLS):

Dawn/dusk
Darkness
Driving through a tunnel
Precipitation such as rain or snow

If wiper switch condition is on, The RLS in the E46 transmits the information thorough the K-bus to the central light switch. (LSZ).

If the RLS switch position("A") on the LSZ has been selected, the exterior and instrument lights are activated by the LSZ under the following conditions:

One of the above RLS conditions is satisfied.
The front fog lights are switched on.

NOTE: When the wiper switch is in the intermittent position, The RLS knows the switch is on by the frequency of the windshield wipers. (The frequency for the intermittent wipers is 15 wiping cycles per minute. If the wiper switch is in position I or II the RLS knows the wipers are switched on permanently.

Fig 2: [RLS Sensor]

Courtesy of BMW OF NORTH AMERICA, INC.

NOTE: If the front fog light is switched on and one of the above mentioned RLS conditions is satisfied, the exterior lights will only go out after the front fog lights have been turned off.

In addition, the lights are switched on in the event of the following malfunctions.

The RLS has detected a sensor fault.
Communication between the RLS and the LSZ is disturbed.

The following lights are switched by the LSZ:

Terminal R turns on the parking light, the low beam headlight, the license plate light and the instrument lights.
Terminal 15 turns on the parking light, the low beam headlights, the license plate light. In order to switch the parking light on the LSZ switch must be set to parking light position on.
With the ignition switch in the "0" position, the exterior and instrument lights are switched off.

The sensitivity of the RLS can be adjusted by means of the car memory function.

Safety Notice: During bad weather and fog the driver must switch on the fog lights manually. The automatic driving-light control will not turn the fog lights on during bad weather conditions.