Setting pushbutton unit illumination, function - GF54.30-P-2010GZ

MODEL 164 up to Model Year 8

Fig 1: Setting Pushbutton Unit Illumination Communication Diagram

Courtesy of MERCEDES-BENZ USA

Data flow image for circuit 58d

Function requirements:

The switch and controls illumination is activated by the following components:

Switching on vehicle lighting (so long as side lights are active)
Automatic running lights by means of the rain/light sensor (B38/2)

When the standing lamp is switched on the position of the Instrument and controls illumination button, dim (A1s5) or Instrument and controls illumination button, bright (A1s4) is used as a controlled variable by the overhead control panel control unit (N70). The rain/light sensor (B38/2) is not taken into account.

When automatic driving lights are on, the brightness of the switch and controls illumination is determined via the rain/light sensor (B38/2).

Its signals are analyzed by the overhead control panel control unit (N70) and the intensity is regulated in this way by the control unit.

Presentation of duty cycle

Fig 2: Duty Cycle Graph

Courtesy of MERCEDES-BENZ USA

Terminal 58d on/off ratio

The lamps of the switch and controls illumination are actuated by means of a square-wave voltage U58d (see top illustration):

The lamps are energized in the time t1, this is then followed by a break. The lamps are energized again after the break and so on.
The change occurs so quickly as to remain imperceptible to the human eye.
The ratio of times t₁ to T is called the duty cycle. where T is the constant cycle duration and t₁ is the time during which power flows during a cycle.
The greater the duty cycle (that is to say the power flow duration t₁ )), the greater the average power and therefore the brighter the lamps.

The voltage curve U58d is sketched in the illustration as it is applied to the outputs "Circuit 58d" of the various control units. The upper sketch shows a duty cycle of 80 %, the lower a duty cycle of 40 %. A duty cycle of 100 % corresponds to normal direct voltage. Power is not supplied when the duty cycle is 0 %.

Advantages of this type of illumination adjustment:

Considerably more efficient,
The brightness of the lamps remains independent of the number of lamps.
every control unit connected to the interior or engine compartment CAN can trigger lamps with the intensity specified by the instrument cluster (A1).

When the standing lamp is "OFF" the instrument cluster (A1) transmits the message "duty cycle circuit 58d = 0 %".

When the standing lamp is "ON" the duty cycle transmitted can be adjusted between 12 % and 100 % using the Instrument and controls illumination button, dim (A1s5) or instrument and controls illumination button, bright (A1s4).

Coolant/washer fluid level voltage coding, function

GF54.30-P-4001GZ