Instrument Cluster (IC), Networking of Components

The instrument cluster (A1) is connected to the CAN/engine compartment and to other control modules, switches etc. via discrete lines.
In addition there is a CAN data bus which exchanges information between the instrument cluster (A1) and radio (A2) or COMMAND operating, display and control module (A40/3). It is abbreviated to "CAN (A1 - A2, A40/3)".

The key CAN messages are listed here for the functions of the instrument cluster (A1) including the trip computer and ASSYST. The key discrete connections of the instrument cluster (A1) are described in the final section of this document.

Receive messages for display instruments and internal further processing:
- The four wheel speeds come from the traction systems control module (N47) via the CAN/engine compartment
- The engine speed signal comes from the injection system control module (N3) via the CAN/engine compartment
- Shift range, selector lever position, drive program come from the ETC control module (N15/3) via the CAN/engine compartment
- The coolant temperature comes from the injection system control module (N3) via the CAN/engine compartment
- The fuel consumption signal comes from the injection system control module (N3) via the CAN/engine compartment
- The oil level (not for vehicles with engine 111 comes from the injection system control module (N3) via the CAN/engine compartment
- The oil temperature (not for vehicles with engine 111) comes from the injection system control module (N3) via the CAN/engine compartment
- On vehicles with COMMAND: The time comes via CAN (A1 - A40/3)
- Signals from the multifunction steering wheel buttons

Signals for indicator and warning lamps:
- The signal for the left and right turn signal indicator lamps (A1e1, A1e2)) comes from the light module (N7-1) via a discrete line for all types of turn signal.
- The signal for the high beam indicator lamp (A1e3) comes from the light module (N7-1) via a discrete line.
- The signal for the low brake fluid level/parking brake indicator lamp (A1e7) comes from the traction Systems control module (N47) via the CAN/engine compartment for the parking brake indicator and for low brake fluid level from brake fluid level switch S11 via a discrete line.
- The signal for the preglow indicator lamp (A1e16) comes from the injection system control module (N3) via the CAN/engine compartment.
- The signal for the ESP warning lamp (A1e41) comes from the traction systems control module (N47) via the CAN/engine compartment.
- The signal for the seat belt reminder lamp (A1e9) comes from the seat belt buckle switch via discrete lines.
- The signal for the engine diagnosis malfunction indicator lamp or "CHECK ENGINE" MIL (A1e58 or A1e26) comes from the injection system control module (N3) via the CAN/engine compartment.
- The airbag indicator and warning lamp (A1e15) is actuated directly via a disrete line.

Signals and receive messages for the multifunction display (A1p13):
- The signals for the messages in the multifunction display (A1p13) come via the CAN/engine compartment or disrete lines.
The signal paths and further details on the individual messages can be found in the function descriptions of the particular systems.

The most important send messages from the instrument cluster (A1) to the CAN/engine compartment are:
- Outside temperature signal
- Fuel tank level
- Terminal 58d
- Terminal 61e
- Engine shut-off time
- Winter tires - maximum speed

The most important send messages of instrument cluster (A1) to the CAN (A1 - A2, A40/3):
- Button status of multifunction steering wheel,
- Button status of language control system (LCS) switch (S93/2)

Discrete lines go from the instrument cluster
- to the brake fluid level switch (S11),
- to the seat belt buckle switch,
- to the light module (N7-1)
- to the multifunction steering wheel,
- to the SRS control module (N2/7)
- to the operating system for the center and side air outlet flap control module (TAC, AAC) (N18/2),
- to search illumination consumers
- to the engine coolant level indicator switch (S41) and windshield washer fluid level indicator switch (S42),
- to the language control system (LCS) switch (S93/2)
- to the generator (G2).
- to the DI control module (N73),
- for the voltage supply.
- to the hydraulic fluid level switch (S77/2)