Power supply for CID, Central Information Display

More detailed functional description, see BMW Service Technology: TIS -> Document -> SI Technology -> Enter SBT number
SBT number: -> 620103027

CID power supply lines:

The Central Information Display (CID) is the indicating instrument of the head unit; it does not generate its own screen contents. The CID is switched on and off using the head unit and is supplied via the following connections:

• Earth connection
  
• Terminal 30g
  
• K-CAN connection (logical control)
  
• LVDS data line (picture signals from the head unit)
  

CID screen failure:

In the event of a temporary screen failure during operation with simultaneous failure of sound output, the CID is not defective. In this case, the function of the head unit 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 code memory entry with regard to the LVDS data line, the operability of the head unit must be checked first.

Faults with regard to back lighting:

The back lighting of the CID is influenced via the bus from the head unit. If the CID does not switch on its back lighting 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 unfavourable operation conditions, the temperature of the CID can rise strongly.

In this case, the CID lowers its brightness. In extreme cases, the CID even switches off its back lighting. If it is switched off, a fault code memory entry is placed in the CID.

Reasons for excessive temperatures in the CID can be:

• High outside temperature
  
• Strong sunlight
  
• Strong heat from the heating duct
  

Faults with regard to brightness

The brightness of the CID is controlled depending on various signals. Brightness of the CID 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 CID. 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 CID, it reduces the brightness.
  
• The brightness of the CID is controlled depending on the signal terminal 58g as soon as the light is switched on.
  
• The brightness of the CID is controlled depending on the light intensity registered by the built-in photosensor.
  

Pixel faults

At the moment, pixel faults cannot be fully excluded for technical production reasons; if the tolerance limit is kept, such faults do not justify replacement. 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 CID is recognised as defective.