Power Supply For FD (Rear Display)

Power Supply For FD (rear display)

FD supply lines:
The rear display (FD) is the indicating instrument of the rear monitor. It does not generate any screen contents.
The FD is switched on and off using the rear monitor and is supplied via the following connections:
- Earth connection
- Terminal 30 g
- K CAN connection (logical control)
- LVDS data line (picture signals from the headunit)
- Data line of the infrared receiver of the headphones

FD screen failure:
In the event of a temporary screen failure during operation with simultaneous failure of sound output, the FD is not faulty. In this case, the function of the rear monitor must be checked first. The same applies to delayed switch-on, frozen graphics or partially hidden image contents.

Faults with regard to LVDS data line:
If there is a fault entry with regard to the LVDS data line, the operability of the rear monitor must be checked first.

Faults with regard to backlighting:
The backlighting of the FD is influenced via the bus from the head unit. If the rear monitor does not switch on its backlighting at terminal 15, a check must be run as to whether the head unit and K CAN are operating without faults.

Faults with regard to excess temperature
With unfavorable operating conditions, the temperature of the FD can rise strongly.
In this case, the FD lowers its brightness. In extreme cases, the FD even switches off its backlighting. If it is switched off, a fault entry is placed in the FD.
Reasons for excessive temperatures in the FD can be:
- High ambient temperature
- Strong sunlight
- Strong heat from the heating duct

Faults with regard to brightness
The brightness of the FD is controlled depending on various signals. Brightness of the FD to which the customer is not accustomed can lead to complaints. In this case, take account of the following causes:
- An individual brightness value can be set for the FD. The brightness value is set at the controller via menu guidance. The set brightness value depends on the ignition key.
- Under certain circumstances, the set brightness value can be reset after programming or after undervoltage.
- At very high temperatures in the FD, it reduces the brightness.
- The brightness of the FD is controlled depending on the signal terminal 58g as soon as the light is switched on.
- The brightness of the FD is controlled depending on the light intensity registered by the built-in photo diode.

Pixel faults
From a production point of view, pixel faults cannot be completely ruled out and are no reason for replacement if they are within the tolerance limit. The following list shows the permitted number of pixel faults:
- Maximum of 2 pixel faults (red) permitted.
- Maximum of 1 pixel fault (green) permitted.
- Maximum of 3 pixel faults (blue) permitted.
- Maximum of 3 pixel faults (total of red, green and blue) permitted.
- If the gap between two pixel faults is closer than 5 mm, the FD is recognized as faulty.