COMAND operating, display and controller unit, component description - GF82.85-P-3134GA

MODEL 463.249 /271 up to 31.8.08 as of model year 2007 

Location 

The COMAND operating, display and controller unit is in the center console.

Task 

The COMAND operating, display and controller unit is the interface between Media Oriented System Transport (MOST) and interior CAN. It is the master control unit for managing all the audio sources as well as all the entertainment and communication systems integrated in the vehicle and centrally controls the following integrated systems:

• DVD drive for map navigation
• Radio tuner
• Basic audio amplifier (4 x 40 watt with Digital Signal Processing (DSP) technology)
• CD drive for audio function (CD, CD-R, CD-RW, MP3, Red Book Audio, Windows Media Audio (WMA) and Advanced Audio Coding (AAC)) with CD text support

With the aid of DSP technology, audio traces are processed using mathematical algorithms with the objective of improving the acoustic tone qualities.

The COMAND operating, display and controller unit also supports the following external function components:

• Voice control system control unit (A35/11)
• Universal Portable Cell Phone Interface (UPCI [UHI]) control unit (N123/1)
• SDAR control unit (N87/5)
• CD changer radio (N87/2)
• Multifunction display (A1p13) in the instrument cluster (A1) (as of model year 07.5, YoM 07)
• Sound system amplifier (N40/9)

Design 

The COMAND operating, display and controller unit is a 2-Deutsche Industrie-Norm (DIN) device and consists of the following components:

• 6.5 color display with 16:9 format
• CD and DVD drives (access via electronically controlled display kinematics)
• Operating unit with hard keys and soft keys for controlling:
  • Audio: radio, CD, CDC, AUX input and satellite radio (SDAR)
  • Navigation: DVD
  • Communication: telephone and SMS (read only)
  • System settings
• Radio tuner (FM/AM/WB) (WB = weatherband)
• Basic audio amplifier
• Navigation processor with global positioning system (GPS) receiver and vibration gyroscope
• Light sensor for dimming the display illumination
• AUX jack in the glove compartment for an external analog audio source

Function 

As of model year 07.5, YoM 07 the COMAND operating, display and controller unit can also be operated via the left multifunction steering wheel button group (S110) and via the right multifunction steering wheel button group (S111).

The brightness of the color display is regulated internally by:

• Soft startup after switching on the illumination
• Phototransistor as a function of the ambient brightness during day mode
• Circuit 58d (instrument illumination, brightness information via interior CAN) during night mode
• Additional brightness correction possible via instrument illumination variable resistor (A1r1)
• Temperature sensor for low temperatures

Navigation module:

The navigation functions run in the navigation module of the COMAND operating, display and controller unit. Location determination is carried out using GPS. For this purpose, a GPS receiver and a turn rate sensor are integrated in the navigation module, in addition to the DVD drive.

Navigation module components:

• The GPS receiver receives the longitude and latitude as well as the Universal Time Coordinated (UTC) time via the GPS satellites
• The left front GPS antenna (A2/23), which is installed under the left headlamp trim

• The turn rate sensor, a piezo-electric vibration gyroscope for detecting any changes in direction (e.g. when cornering)
• Wheel pulse counter (RIZ) signal via interior CAN for determining the route traveled

Calculation of navigation algorithms by:

• Evaluation of GPS data
• Evaluation of wheel pulse counter (RIZ) signal
• Evaluation of turn rate data (cornering)
• Interlinked satellite navigation

Display movements of the COMAND operating, display and controller unit 

Pressing the "EJECT" button moves the display downward and provides easy access to the DVD drive and the CD drive. The display is closed by pressing the "EJECT" button again.

Emergency eject

If the CD or DVD cannot be ejected, press the relevant "EJECT" button next to the DVD drive or the CD drive and hold it down until the DVD or CD is ejected.

Diagnosis: 

Diagnosis takes place from the EIS [EZS] control unit (N73) to the COMAND operating, display and controller unit.

All other control units in the MOST ring are also diagnosed via this interface.

The following can be selected:

• Available frequency bands (FM/AM/WB)
• The start and stop frequencies (bandwidth)
• The frequency raster (tuning steps)
• Speed-dependent volume control (SDV [GAL])
• The shut-off time, with circuit 15 Off

Software download (flashing)

• Update-CD for the unit properties
• Update-DVD for the navigation properties

Signal inputs and outputs 

Discrete inputs 

• Circuit 30
• Circuit 31
• Wake-Up
• AUX input
• Left front GPS antenna
• Amplifier module 1, window antenna (A2/71)

Discrete outputs 

• Remote antennas
• Audio out (speaker)

The speakers are only connected directly to the COMAND operating, display and controller unit if there is no sound system amplifier (N40/9) installed.

MOST signals 

Control, data and audio signals are received via MOST from the following components:

• SDAR control unit
• Voice control system control unit
• Universal Portable Cell Phone Interface (UPCI [UHI]) control unit
• CD changer radio

CAN signals 

The COMAND operating, display and controller unit is a subscriber of the interior CAN.