Instrument Cluster (IC), Networking of Components

Instrument Cluster (IC), Networking Of Components
The instrument cluster (A1) is linked to the engine compartment CAN and the interior compartment CAN. Data is exchanged with both bus systems and with almost all the control modules on the two bus systems.

NOTE: However, the instrument cluster (A1) does not act as an interface (gateway) between the two data bus systems. This function is reserved for the EIS control module (N73).

This information lists the principal CAN messages for the functions of the instrument cluster (A1) including the trip computer and ASSYST system.
The connections of the instrument cluster (A1) are described in the last part of this information.

Received messages for display instruments and internal processing:
- The four wheel speeds; over the engine compartment CAN from the SBC control module (A7/3n1)
- Engine speed signal; over the engine compartment CAN from the ME-SFI control module (N3/10)
- Shift range, selector lever position, transmission mode; over the engine compartment CAN from the electronic selector lever module control module (N15/5) or from the automated manual transmission control module (N15/6)
- Fuel level; over the interior compartment CAN from the rear SAM control module (N10/8)
- Coolant temperature; over the engine compartment CAN from the ME-SFI control module (N3/10)
- Fuel consumption signal; over the engine compartment CAN from the ME-SFI control module (N3/10)
- Oil level; over the engine compartment CAN from the ME-SFI control module (N3/10)
- Oil temperature; over the engine compartment CAN from the ME-SFI control module (N3/10)
- Outside temperature signal; over the interior compartment CAN from the driver-side SAM control module (N10/10)
- Standing lamps ON/OFF; over the interior compartment CAN from the driver-side SAM control module (N10/10)
- Coolant; driver side SAM control module (N10/10)
- Washer fluid level; over the interior compartment CAN from the passenger-side SAM control module (N10/11)
- In vehicles with COMAND: The time; over the interior compartment CAN from the COMAND operating, display and control module (A40/3)
- States Terminal 15" and "Key in ignition"; over the interior compartment CAN from the EIS control module (N73).
- Signals from the buttons on the multifunction steering wheel;

Received messages for indicator and warning lamps:
- Signal for left turn signal indicator lamp (A1e1) and right turn signal indicator lamp (A1e2);
- for direction indicating over the interior compartment CAN from the steering column module (N80)
- for hazard warning flasher over the interior compartment CAN from the lower control panel control module (N72)
- for ATA flashing over the interior compartment CAN from the driver-side SAM control module (N10/10)
- Signal for high beam indicator lamp (A1e3); over the interior compartment CAN from the driver-side SAM control module (N10/10)
- Signal for brake fluid and parking brake warning lamp (A1e7); over the interior compartment CAN from the driver-side SAM control module (N10/10)
- Signal for ESP and ABS warning lamp (A1 e41); over the engine compartment CAN from the ESP, SPS and BAS control module (N47-5)
- Seat belt warning lamp (A1e9); over the interior compartment CAN from the left and right front seat adjustment control modules with memory (N32/1 and N32/2)
- Signal for engine diagnosis indicator lamp (A1e58) or CHECK ENGINE malfunction indicator lamp (A1e26); over the engine compartment CAN from the ME-SFI control module (N3/10)
- Signal for DTP warning lamp and indicator lamp DTK (A1e59); over the engine compartment CAN from the DTR control module (N63/1)

NOTE: The airbag indicator and warning lamp (A1e15) is actuated not over CAN, but over a discrete line!

Received messages for the left multifunction display (A1p13) and right multifunction display (A1p15)
- All signals for the messages in the left and right multifunction displays (A1p13 and A1p15) are received over the engine compartment CAN or the interior compartment CAN. Information about the signal paths and other details concerning the individual messages can be found in the function descriptions for the relevant systems.

Transmitted messages from the instrument cluster (A1):
- Displayed vehicle speed; to the interior compartment CAN
- Current time; to the interior compartment CAN
- Temperature units (degree C/degree F); to the interior compartment CAN
- Headlamp switching manual/always-on (ON/OFF); to the interior compartment CAN
- Interior light courtesy delay to the interior compartment CAN
- Headlamp switch-off delay to the interior compartment CAN
- Outside temperature signal; to the engine compartment CAN
- Terminal 58d; to the engine compartment CAN and the interior compartment CAN
- Terminal 61e; to the engine compartment CAN
- Engine OFF time; to the engine compartment CAN
- Winter tires maximum speed; to the engine compartment CAN
- Signals from the buttons on the multifunction steering wheel;

CAN messages from buttons on the multifunction steering wheel
Since the buttons on the multifunction steering wheel each have several functions, the signals from these buttons must be processed 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) sends the relevant messages over the interior compartment CAN.
- These CAN messages are received by the instrument cluster (A1).
- The instrument cluster (A1) interprets these messages in conjunction with the systems currently displayed in the left and right multifunction displays (A1p13 and A1p15) and relays these interpreted messages back over the interior compartment CAN as another message.
- This interpretation is necessary because the operation of some of the buttons depends on the current content of the multifunction display.
Example:
When the driver presses the + and - button for setting of specific functions and volume control (S111s1) on the multifunction steering wheel in the (+) direction, the volume of the sound system is usually increased. However, if the right multifunction display (A1p15) 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 compartment 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 compartment CAN)
- CAN-B HIGH (interior compartment CAN)

- Terminal 31 (ground)

- Terminal 30 (battery positive, supplies voltage to almost all the electronics of the instrument cluster)

- Terminal 15r (switched positive, supplies voltage to the airbag indicator and warning lamp (A1e15) and the diagnostic interface of the instrument cluster (A1))

- K-line This line is connected to the diagnostic data link connector (X11/4). It carries the data when diagnosing the instrument cluster (A1) with the STAR Diagnosis tool.

- Input for the airbag indicator and warning lamp (A1e15);
this input is connected directly to the corresponding output of the restraint systems control module (N2/7).
- Terminal 31 Electronic clock (A70) ground
- Terminal 15g Control input for limp-home mode
- Terminal 30 Electronic clock (A70) supply, output and battery
- K-line Diagnosis line
- LIN bus Electronic clock (A70) data line