GF82.20-P-2029Q Instrument Illumination, Function

GF82.20-P-2029Q Instrument Illumination, Function

With instrument illumination a distinction must be made between:
^ Function illumination
^ Switch and controls illumination

The function illumination (display and symbol illumination of the instrument cluster (A1) and the operating modules equipped with a display panel, e.g. radio, air conditioning) is activated by switching on the ignition "circuit 15R ON".
The switch and controls illumination (illumination of controls, switches and buttons) is activated by switching on the exterior lights "circuit 58d".
The brightness of the function illumination and switch and controls illumination can be preset individually in the instrument cluster (A1) via the instrument illumination dimmer and reset button (A1r1).

The automatic light functions are dependent on the rain/light sensor (B38/2). Its signals are evaluated by the overhead control panel control unit (N70). Depending on the ambient brightness the rain/light sensor (B38/2) produces the CAN message "Night" or "Day".
When the exterior lights are switched on and thus the switch and controls illumination is activated, the instrument cluster (A1) also adapts the switch and controls illumination to the ambient light conditions.
As the brightness of the function illumination must be higher during the day than in darkness, in addition a distinction is made between a day and night brightness value. For this purpose the instrument cluster (A1) evaluates the "Day" or "Night" signals determined by the overhead control panel control unit (N70) via the rain/light sensor (B38/2) and transmitted to the data bus.

The function illumination and switch and controls illumination, e.g. of the radio or air conditioning, can be activated by switching on the corresponding control also without ignition "circuit 15R ON". The brightness of the illumination varies according to the brightness value of the instrument illumination dimmer and reset button (A1r1) preset in the instrument cluster (A1). The function illumination is adjusted by the rain/light sensor (B38/2) corresponding to the prevailing light conditions. Once the ignition is switched off "circuit 15R OFF" the instrument cluster (A1) stores the last available adjustment value from the instrument illumination dimmer and reset button (A1r1).

Function when function illumination is actuated during the day
The transmitter key (A8/1) is switched to position "circuit 15R ON" in the electronic ignition switch control unit (N73). The instrument cluster (A1) is actuated by the signal "circuit 15R ON" via the data bus and immediately activates the function illumination with the last stored adjustment value from the instrument illumination dimmer and reset button (A1r1).

The overhead control panel control unit (N70) receives the "day" signal from the rain/light sensor (B38/2) and transmits a CAN message to the instrument cluster (A1) via the interior CAN. The instrument cluster (A1) then actuates the function illumination with the bright day brightness value, the rain/light sensor (B38/2) constantly measuring the ambient light conditions and adapting the brightness of the function illumination.

Function sequence when the switch and controls illumination is actuated
Basic conditions:
^ The ignition "circuit 15R ON" and the function illumination is activated.
^ It is "night" and the instrument cluster (A1) actuates the function illumination with the dark night brightness value.

The standing lamp or low beam is switched on manually at the exterior lamp switch in the light switch module (S1) or via the automatic driving light actuation.

The front SAM control unit with fuse and relay module (N10/1) transmits the CAN message "standing lamp ON" or "low beam ON" to the instrument cluster (A1) via the interior CAN. The instrument cluster (A1) actuates the switch and controls illumination with the brightness value of the instrument illumination dimmer and reset button (A1r1) currently adjusted for the function illumination.

Irrespective of the day or night brightness value, the switch and controls illumination is adapted and actuated individually to the current ambient light condition depending on the preset brightness value of the instrument illumination dimmer and reset button (A1r1) in the instrument cluster (A1).