Indicator/warning messages, function

General function requirements

 Instrument cluster (A1) activated

Indicator and warning messages in general

The instrument cluster (A1) indicator and warning messages notifies the driver about the current states of the systems installed in the vehicle.

The instrument cluster can output indicator and warning messages in the following ways:

- Visual indicator/warning messages

- Acoustic indicator/warning messages

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Visual indicator/warning messages:

The visual indicator and warning messages are displayed using the following instrument cluster components:

- Multifunction display (A1p13)

- Indicator/warning lamps

Audible indicator/warning messages:

The audible indicator and warning messages are displayed using the following instrument cluster components:

- Warning buzzer (A1h1)

- Audible turn signal indicator (A1h2) (turn signal clicking)

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The warning messages shown on the multifunction display are divided up into three categories:

- Category 1 (warning messages of the highest priority)
These warning messages cannot be acknowledged and canceled.
When they occur, a short warning tone is issued via the warning buzzer and the fault is displayed in the multifunction display. Any category 2 and 3 warning messages are cross-faded.

- Category 2 (warning messages of medium priority)
These warning message can be acknowledged and canceled using the trip odometer reset button (A1s3).
When they occur, a short warning tone is issued via the warning buzzer and the fault is displayed in the multifunction display. Any category 3 warning messages are cross-faded.

- Category 3 (warning messages of the lowest priority)
These warning message can be acknowledged and canceled using the trip odometer reset button. There is no warning tone.
These messages are divided into two subcategories and stored in the U and W-roll memories.

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The U-roll memory is the directory of all unacknowledged warning messages which are shown in the multifunction display.

Warning messages of the same or higher priority are faded in after the expiry of the minimum display time of the preceding warning message.

Once the minimum display time for the warning message with the lowest priority the fault roll starts again at the warning message with the highest priority.

All warning messages in the U-roll memory are displayed with increased brightness.

All the warning messages which occurred during the journey and were acknowledged are entered in the W-roll memory.

The W-roll memory can be accessed at any time in the Settings menu of the multifunction display. Once the memory is called up, an initial picture is first displayed with the number of warning messages which occurred. The warning messages are then displayed in their priority order.

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The indicator and warning messages are made up as follows:

 Function sequence for cruise-control control messages

 Function sequence for indicator/warning messages for the Electronic Stability Program (ESP)

 Function sequence for indicator/warning messages for the antilock brake system (ABS)

 Function sequence for indicator/warning messages for the supplemental restraint system (SRS)

 Function sequence for indicator/warning messages for the exterior lights (ABL)

 Function sequence for indicator/warning messages for the on-board electrical system management

 Function sequence for indicator/warning messages for the tire pressure loss warning (RDW)
(with code (477) Tire pressure loss warning)

 Memory adjustment
(with code (275) Memory package (driver seat, steering column, mirrors))

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 Function sequence for audio/communication/navigation control messages
(with code (523) MB Audio 20 radio or with code (525) MB Audio 50 APS radio or with code (527) COMAND APS with single DVD drive (with navigation))

 Door open reminder warning function sequence

 Function sequence, lights on reminder warning

 Parking brake warning function sequence

 Function sequence for seat belt reminder warning

 Function sequence for coolant level and coolant temperature warning

 Function sequence, engine oil level warning

 Function sequence for preglow indicator lamp (with diesel engine)

 Function sequence for brake fluid level warning message

 Function sequence for brake lining wear display warning message

 Function sequence for windshield washer system fluid level warning

 Function sequence, turn signal confirmation

 Function sequence for engine control warning message

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Additional function requirements for cruise-control control messages

 Vehicle speed v > 30 km/h

Function sequence for cruise-control control messages

The cruise-control control messages partial function is made up of the following subfunctions:

 Function sequence for cruise-control control message

 Function sequence for limiter control message

 Function sequence for permanent limiter control message

Function sequence for cruise-control control message

If the cruise control was activated using the CC [TPM] push button (S40/4), the set vehicle speed is shown in the multifunction display.

Function sequence for limiter control message

If the limiter was activated using the CC [TPM] push button, the set vehicle speed limit is shown in the multifunction display.

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Function sequence for permanent limiter control message

The instrument cluster can be used to set the vehicle speed permanently to a value between 160 km/h (e.g. when running on winter tires) and limit the maximum speed.

Additional function requirements for ESP indicator/warning messages

 Circuit 61 ON

Function sequence for ESP indicator/warning messages

For a passively connected ESP or for an ESP control intervention function, the ESP warning lamp (A1e41) is actuated by the instrument cluster.

In the event of error messages from the ESP and BAS control unit (N47-5) a warning message is shown on the multifunction display. The ESP can be passively connected by pressing the ESP OFF switch (N72/1s1) when the engine is running. The status of the ESP OFF switch is read in by the upper control panel control unit (N72/1) and sent to the instrument cluster on the interior CAN.

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ESP control intervention functions and error messages are sent by the ESP and BAS control unit over the engine compartment-CAN to the instrument cluster.

Additional function requirements for ABS indicator/warning messages

 Vehicle speed v > 0 km/h

Function sequence for ABS indicator/warning messages

If there is a fault in the ABS, the ESP and BAS control unit sends a corresponding signal over the engine compartment-CAN to the instrument cluster. In response, the instrument cluster actuates the ABS indicator lamp (A1e17) and displays a warning message on the multifunction display.

Additional function requirements for SRS indicator/warning messages

 Circuit 15 On

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Function sequence for SRS indicator/warning messages

If there is a fault in the SRS, the supplemental restraint system control unit (N2/7) sends a corresponding signal over the interior-CAN to the instrument cluster. In response the instrument cluster actuates the airbag indicator and warning lamp (A1e15).

Additional function requirements for exterior lighting (ABL) indicator/warning messages

 Circuit 15 On

 Circuit 58 ON

Function sequence for ABL indicator/warning messages

The active standing lights or low beam actuation is confirmed to the driver through the low beam indicator lamp (A1e67) and the active high beam actuation over the high beam indicator lamp (A1e3). The corresponding status message is sent to the instrument cluster by the front SAM control unit with fuse and relay module (N10/1) over the interior CAN.

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The function of the lamps for the exterior lights is checked by the following control units:

- Front SAM control unit

- Rear SAM control unit with fuse and relay module (N10/2)

- Left front door control unit (N69/1)

- Right front door control unit (N69/2)

Any failure is notified to the instrument cluster by the corresponding control unit over the interior CAN. In response the instrument cluster actuates the bulb failure warning lamp (A1e14) and displays a corresponding warning message over the multifunction display.

Additional function requirements for on-board electrical system management

 Circuit 15 On

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Function sequence for indicator/warning messages for the on-board electrical system management

In the event of any faults in the on-board electrical system (e.g. defective alternator (G2)) a corresponding warning message is shown on the multifunction display. The information on the alternator function is sent to the instrument cluster by the engine compartment-CAN from the CDI control unit (N3/9) (with diesel engine) or from the ME-SFI [ME] (N3/10) (with gasoline engine).

Additional function requirements for tire pressure loss warning system

 Vehicle speed v > 0 km/h

Function sequence for indicator/warning messages for the tire pressure loss warning system

A pressure loss at one of the tires is recognized by the change in wheel circumference and the associated change in wheel speed. The ESP and BAS control unit reads in the signals from the left front rpm sensor (L6/1), right front rpm sensor (L6/2), left rear rpm sensor (L6/3) and the right rear rpm sensor (L6/4).

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If a significant pressure loss or a system malfunction is detected, the ESP and BAS control unit sends a corresponding signal over the engine compartment-CAN to the instrument cluster. In response the instrument cluster shows a corresponding warning message on the multifunction display.

Function sequence for memory adjustment control message

The instrument cluster outputs an acknowledgment tone through the warning buzzer when a memory position is stored. The request to emit this acknowledgment tone is sent by the driver-side front seat adjustment control unit with memory (N32/1) or from the passenger-side front seat adjustment control unit with memory (N32/2) (with code (242) electrically adjustable front passenger seat with memory) over the interior CAN to the instrument cluster.

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Additional function requirements for audio/communication/navigation control messages

 Circuit 15 On

Function sequence for audio/communication/navigation control message

The multifunction display shows information on the communication systems installed in the vehicle.

The instrument cluster receives the information from the radio (A2) (with code (523) MB Audio 20 radio), from the radio and navigation unit (A2/56) (with code (525) MB Audio 50 APS radio) or from the COMAND operating, display and controller unit (A40/3) (with code (527) COMAND APS with single DVD drive (with navigation)) over the interior CAN.

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Additional function requirements, door open reminder warning

 Vehicle speed v > 3 km/h

Function sequence, door open reminder warning

If at a vehicle speed of v > 3 km/h an open door, liftgate or engine hood (with code (551) Antitheft alarm system ATA [EDW]) is detected, the instrument cluster actuates the warning buzzer and also shows a corresponding warning message on the multifunction display.

The status of the left door is recognized by the left front door contact switch (S17/3), the status of the right door by the right front door contact switch (S17/4), the status of the liftgate by the rotary tumbler locking pawl switch (S88/4) and the status of the engine hood by the ATA [EDW] engine hood switch (S62) (with code (551) Antitheft alarm system ATA [EDW]). The respective status is read in by the rear SAM control unit and sent over the interior CAN to the instrument cluster. The instrument cluster then actuates the warning buzzer.

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Additional function requirements, lights on reminder

 C. 15C OFF

 Circuit 58 ON

Function sequence, lights on reminder warning

If at circuit 15C OFF with the standing lights/low beams switched on, the driver door is opened, the instrument cluster then actuates the warning buzzer and also displays a corresponding warning message on the multifunction display.

The status of the standing lights/low beam actuation is sent by the front SAM control unit over the interior CAN to the instrument cluster. The status of the door contact switch is read in by the rear SAM control unit and sent over the interior CAN to the instrument cluster.

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Additional function requirements, parking brake on reminder warning

 Vehicle speed v > 5 km/h

Parking brake warning function sequence

If, at a vehicle speed of v > 5 km/h, the parking brake inspection switch (S12) is operated, the instrument cluster actuates the warning buzzer and also displays a corresponding message on the multifunction display. The brake fluid and parking brake warning lamp (A1e7) is also actuated.

The status of the parking brake inspection switch is read by the front SAM control unit and transmitted via the interior CAN to the instrument cluster.

Additional function requirements for seat belt reminder warning

 Circuit 61 ON

 Driver or front passenger seat belts not inserted

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Function sequence for seat belt reminder warning

To display the seat belt reminder warning the restraint system control unit evaluates the signals for the following components:

- Driver side seat belt buckle restraint systems switch (S68/3)

- Front passenger-side seat belt buckle restraint systems switch (S68/4)

- Assignment status of front passenger seat

 A warning message for the front passenger is only issued, if the front passenger seat is recognized as occupied.

If a seat belt is not fitted, the restraint system control unit sends a corresponding signal over the interior CAN to the instrument cluster, which then actuates the seat belt warning lamp (A1e9).

If the vehicle is moving at (v > 0 km/h), the following warning tone phase is initiated.

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1st. warning tone phase:

A quiet gong is sounded for a maximum t = 20 s at an interval of
t = 2 s.

After this a change is automatically made to the 2nd. warning tone phase.

2nd. warning tone phase:

A quiet gong is sounded for a maximum t = 20 s at an interval of
t = 1 s.

After this a change is automatically made to the 3rd. warning tone phase.

3rd. warning tone phase:

A quiet gong is sounded for a maximum t = 20 s at an interval of
t = 0.4 s.

After this a change is automatically made to the 4th. warning tone phase.

4th. warning tone phase:

A loud gong is sounded for maximum t = 93 s at an interval of
t = 0.5 s.

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 When a warning tone is emitted the seat belt warning lamp is actuated and it flashes on and off. Once all the warning tone phases have been passed through it is actuated permanently.

The seat belt reminder warning is deactivated under the following circumstances:

- When a seat belt that was not fitted is then fitted

- Vehicle at standstill and driver or front passenger door is opened

The seat belt reminder warning is activated again under the following circumstances:

- Warning tone phases for the driver are completely finished and the front passenger removes his/her seat belt

- Vehicle at standstill and driver or front passenger door opened and then closed again

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Additional function requirements for coolant level and coolant temperature warning

 Circuit 15 On

Function sequence for coolant level and coolant temperature warning

The coolant level in the expansion reservoir is monitored by the coolant level indicator switch (S41).

The status of the coolant level indicator switch is read in by the front SAM control unit. If the coolant level is too low the front SAM control unit sends a corresponding signal over the interior CAN to the instrument cluster. In response the instrument cluster shows a warning message on the multifunction display.

The coolant temperature is recorded by the coolant temperature sensor (B11/4). The signals of the coolant temperature sensor are read in by the CDI control unit (with diesel engine) or from the ME-SFI [ME] control unit (with gasoline engine).

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If the coolant temperature is too high the CDI control unit CDI or the ME-SFI [ME] control unit sends a corresponding signal over the engine compartment-CAN to the instrument cluster. The instrument cluster then actuates the coolant temperature indicator lamp (A1e54).

Additional function requirements for engine oil level warning

 Circuit 15 On

Engine oil level warning function sequence

To monitor the engine oil level, the engine oil temperature and the engine oil pressure is installed in the oil pan of the oil level check switch (S43). The signals of the oil level check switch are read in by the CDI control unit or the ME-SFI [ME] control unit. If necessary, the CDI control unit or the ME-SFI [ME] control unit sends a corresponding signal over the engine compartment-CAN to the instrument cluster, whereupon the instrument cluster then displays a corresponding warning message on the multifunction display.

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Additional function requirements, preglow indicator

 Circuit 15 On

Function sequence for preglow indicator lamp (with diesel engine)

During the preglow phase the preglow indicator lamp (A1e16) is actuated by the instrument cluster.

The corresponding signal for the active preglowing process is sent by the CDI control unit over the engine compartment-CAN to the instrument cluster.

Additional function requirements for brake fluid level warning message

 Circuit 15 On

Function sequence for brake fluid level warning message

If the fluid level in the brake fluid reservoir is too low it is detected by the brake fluid check switch (S11). The status of the brake fluid check switch is read in by the front SAM control unit.

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If the fluid level is too low the front SAM control unit sends a corresponding signal over the interior CAN to the instrument cluster. In response the instrument cluster actuates the brake fluid warning lamp and the parking brake and also displays a corresponding warning message through the multifunction display.

Additional function requirements for brake lining wear display warning message

 Circuit 15 On

Function sequence for brake lining wear display warning message

When the brake lining wear limit for the front and rear axles is reached, it is detected by the right front brake pad contact sensor (S10/2) and the right rear brake pad contact sensor (S10/4). The status of the brake pad contact sensor is read in by the ESP and BAS control unit. If the wear limit is exceeded the ESP and BAS control unit sends a corresponding signal over the engine compartment-CAN to the instrument cluster.

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In response the instrument cluster shows a corresponding warning message on the multifunction display.

Additional function requirements for windshield washer system fluid level warning

 Circuit 15 On

Function sequence for windshield washer system fluid level warning

The fluid level in the washer fluid reservoir is monitored by the windshield washer system fluid level indicator switch (S42).

The status of the windshield washer system fluid level indicator switch is read in by the front SAM control unit. If the fluid level is too low the front SAM control unit sends a corresponding signal over the interior CAN to the instrument cluster. In response the instrument cluster actuates the window washer fluid warning lamp (A1e13) and displays a corresponding warning message on the multifunction display.

Function sequence, turn signal confirmation

The acoustic feedback about the active turn signal light actuation is implemented by the acoustic turn signal indicator integrated into the instrument cluster.

The visual feedback takes place via the left turn signal indicator lamp (A1e1) and right turn signal indicator lamp (A1e2).

Additional function requirements for engine control warning message

 Circuit 15 On

Function sequence for engine control warning message

If a malfunction occurs in the diesel fuel injection system, in the ignition system or in the exhaust system, the engine diagnosis indicator lamp (A1e58) is actuated. The signal for actuating the engine diagnosis indicator lamp is sent by the ME-SFI [ME] control unit or from the CDI control unit over the engine compartment-CAN to the instrument cluster.