Instrument cluster (IC), networking of components - GF54.30-P-0002-06S

The instrument cluster (A1) is networked with the engine compartment CAN and the interior CAN. Data is exchanged with both bus systems and with practically all the control units of the two bus systems.

Valid up to 31.8.02 

The instrument cluster (A1) does not, however, act as an interface (gateway) between the two bus systems. This function is reserved for the EIS [EZS] control unit (N73).

Valid as of 01.9.02 

The interface between the interior CAN and the engine compartment CAN is provided by the central gateway control unit (N93).

Below is a list of the CAN messages that are important for the functions of the instrument cluster (A1) including trip computer and ASSYST.

The connections of the instrument cluster (A1) are described in the last section.

Received messages for display instruments and internal processing:

• Four wheel speeds:

  over engine compartment CAN from chassis control unit (N47)

• Engine speed signal:

  over engine compartment CAN from ME-SFI [ME] control unit (N3/10) or CDI control unit (N3/9)

• Shift range, shift lever position, transmission mode:

  over engine compartment CAN from ETC [EGS] control unit (N15/3)

• Fuel tank level:

  over interior CAN from rear SAM control unit (N10/8)

• Coolant temperature:

  over engine compartment CAN from ME-SFI [ME] control unit (N3/10) or CDI control unit (N3/9)

• Fuel-consumption signal:

  over engine compartment CAN from ME-SFI [ME] control unit (N3/10) or CDI control unit (N3/9)

• Oil level:

  over engine compartment CAN from ME-SFI [ME] control unit (N3/10) or CDI control unit (N3/9)

• Oil temperature:

  over engine compartment CAN from ME-SFI [ME] control unit (N3/10) or CDI control unit (N3/9)

• Outside temperature signal:

  over interior CAN from left front SAM control unit (N10/6)

• Standing lamp ON/OFF:

  over interior CAN from left front SAM control unit (N10/6)

• Coolant and washer fluid level:

  over interior CAN from right front SAM control unit (N10/7)

• In vehicles with COMAND:

  the time is read in from the COMAND operating, display and control unit (A40/3) over the interior CAN.

• Status of "circuit 15" and "key in ignition":

  over interior CAN from electronic ignition switch control unit (N73)

• Signals from multifunction steering wheel buttons:

  see separate section

Received messages for indicator and warning lamps:

• Signal for left turn signal indicator lamp (A1e1) and right turn signal indicator lamp (A1e2):

  For turn signals from steering column module (N80) over interior CAN

  For hazard warning flashers from upper control panel control unit (N72/1) over interior CAN

  For anti-theft alarm system from left front SAM control unit (N10/6) over interior CAN

  With special functions from special vehicle multifunction control unit (SVMCU [MSS]) (N26/9) over interior CAN

• Signal for high beam indicator lamp (A1e3):

  from left front SAM control unit (N10/6) or from special vehicle multifunction control unit (SVMCU [MSS]) (N26/9) with model 220 over interior CAN

• Signal for brake fluid level and parking brake (A1e7): over interior CAN from left front SAM control unit (N10/6)
• Signal for preglow indicator lamp (A1e16):

  over engine compartment CAN from CDI control unit (N3/9)

• Signal for ESP warning lamp (A1e41) and ESP indicator lamp (A1e42):

  over engine compartment CAN from chassis control unit (N47)

• Signal for seat belt warning lamp (A1e9):

  over interior CAN from left front seat adjustment control unit with memory (N32/1) or from right front seat adjustment control unit with memory (N32/2)

• Signal for engine diagnosis indicator lamp (A1e58) or "CHECK ENGINE" MIL (A1e26):

  over engine compartment CAN from ME-SFI [ME] control unit (N3/10) or CDI control unit (N3/9)

• Signal for DTR warning lamp (A1e59):

  via engine compartment CAN from DTR control unit (N63/1)

• Signal for tire pressure monitor warning lamp (A1e66), via interior CAN from TPM [RDK] control unit (N88)

The airbag indicator and warning lamp (A1e15) is actuated by a discrete line not via the CAN bus.

Received messages for the multifunction display (A1p13)

• All signals for the messages in the multifunction display (A1p13) are received over the engine compartment CAN or interior CAN.

  Information about the signal paths and other details concerning the individual messages can be found in the function descriptions for the relevant systems.

Messages sent by the instrument cluster (A1):

• Displayed speed:

  to interior CAN

• Current time:

  to interior CAN

• Temperature units (degrees Celsius and degrees Fahrenheit):

  to interior CAN

• Automatic driving light actuation (ON/OFF):

  to interior CAN

• Interior light courtesy delay:

  to interior CAN

• Headlamp switch-off delay:

  to interior CAN

• Outside temperature signal:

  to engine compartment CAN

• Circuit 58 d:

  to engine compartment CAN and interior CAN

• Circuit 61 e:

  to engine compartment CAN

• Engine off time:

  to engine compartment CAN

• Winter tires maximum speed:

  to engine compartment CAN

• Signals from multifunction steering wheel buttons:

  see section below

CAN data of multifunction steering wheel buttons Since the buttons on the multifunction steering wheel each have several functions, the data from these buttons must be processed 114 of 346 accordingly:

• All the buttons in the left multifunction steering wheel button group (S110) and the right multifunction steering wheel button group (S111) are voltage-coded and are read by the steering column module (N80).
• The steering column module (N80) puts the relevant messages onto the interior CAN.
• This CAN data is received by the instrument cluster (A1).
• The instrument cluster (A1) interprets this data in combination with the systems currently displayed on the multifunction display (A1p13) and passes this interpreted data again on the interior CAN.

  This interpretation is necessary because the operation of the some of buttons depends on the current content of the multifunction display (A1p13).

Example: 

If the driver presses the + and -button, setting specific functions and volume control (S111s1) on the multifunction steering wheel, the volume of the sound system is usually increased.

However, if the multifunction display (A1p13) is currently displaying another setting such as the interior light courtesy delay, this setting is changed when the driver presses the "+" button. The volume stays the same.

Connections: 

The linking of the instrument cluster (A1) with the engine compartment CAN and the interior CAN has reduced the number of inputs and outputs (including voltage supply) to the following connections:

• CAN-C Low = engine compartment CAN
• CAN-C High = engine compartment CAN
• CAN-B Low = interior CAN
• CAN-B High = interior CAN
• Circuit 31 Ground
• Circuit 30 Battery positive Supplies the instrument cluster (A1) with power.
• Circuit 15R Switched positive

  Used for the airbag indicator and warning lamp (A1e15) and for the diagnostic interface of the instrument cluster (A1) as a voltage supply.

• K-line

  This line is connection to the data link connector (X11/4). Data is transferred from the instrument cluster (A1) when carrying out diagnosis with the STAR DIAGNOSIS TOOL.

• Input for airbag indicator and warning lamp (A1e15)

  This input is connected directly to the relevant output of the restraint systems control unit (N2/7).