Part 2 of 2
Function sequence, national seat belt reminder warningIf, immediately prior to starting a journey or during a journey, a seat belt is detected to be not fitted, the instrument cluster issues a country-specific optical and acoustic seat belt reminder warning. The instrument cluster evaluates the following information for issuing a country-specific seat belt reminder warning:
- For code (494) USA version:
- Left front seat belt buckle restraint systems switch (S68/3)
- SRS right front seat belt buckle switch (S68/4)
- Front passenger seat occupancy status
- Without code (494) USA version:
- Left front seatbelt buckle microswitch (S68/9)
- Right front seatbelt buckle microswitch (S68/10)
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.
The manner of how the seat belt reminder warning is issued differs in whether the seat belt reminder warning is prescribed by law or not and is incorporated into the assessment through the New Car Assessment Program (NCAP).
NCAP is an assessment program for safety in new vehicles.
- Countries with seat belt reminder warning prescribed by law (extended NCAP): Japan, USA, Canada, Arab States of the Gulf and Korea
- Countries without seat belt reminder warning prescribed by law (Euro NCAP): Europe (ECE), China and Australia.
In countries in which the seatbelt reminder is prescribed by law (extended NCAP), the seat belt warning lamp is activated for a time interval of t = 6 ±2 s. It is irrelevant here whether the driver seat belt is fitted or not.
If the driver's seat belt is not fitted, the instrument cluster also issues an acoustic warning over the internal warning buzzer. To his end, the instrument cluster evaluates the status of the left front seat belt buckle restraint system switch or the left front seat belt buckle microswitch. The restraint system control unit routes this data over the interior CAN to the instrument cluster.
If the driver seat belt is fitted during this time interval, the acoustic warning is canceled.
An assessment of whether the front passenger seat belt is fitted or not given during this time interval.
Only after the time interval of t = 6 s has expired, does the assessment of both seat belts occur.
In countries in which the seat belt reminder warning is not prescribed by law, the seat belt warning lamp is only actuated during the indicator lamp test. As soon as the engine running characteristics (circuit 61 ON) are detected then both the status of the left front seat belt buckle restraint system or the left front seat belt buckle microswitch, and the status of the right front seat belt buckle restraint system switch or the right front seat belt buckle microswitch is evaluated. If a seat belt is defined to not be fitted, the instrument cluster actuates the seat belt warning lamp. If the vehicle starts to move, when it reaches a speed of v ≥25 km/h, further successive acoustic warnings are issued.
Three or four acoustic warnings are issued in accordance with the seat belt reminder warning. While they are being issued the seat belt warning lamp is actuated by flashing it at a frequency of f = 1 Hz. After all the acoustic warning phases have expired the seat belt warning lamp is permanently actuated.
- Acoustic warning phase 1: As the vehicle starts to drive off, acoustic warning phase 1 also starts in the background. When a speed of v ≥25 km/h is reached a quiet acoustic warning is sounded at an interval of t = 2 s. The acoustic warning phase 1 last for a maximum t = 20 s. This is then followed by a transition to acoustic warning phase 2.
- Acoustic warning phase 2: After expiry of acoustic warning phase 1 and as from a speed of v ≥25 km/h a quiet acoustic warning is sounded for maximum t = 20 s at an interval of t = 1 s. This is then followed by a transition to acoustic warning phase 3.
- Acoustic warning phase 3: After expiry of acoustic warning phase 2 and as from a speed of v ≥25 km/h a quiet acoustic warning is sounded for maximum t = 20 s at an interval of t = 0.4 s. This is then followed by a transition to acoustic warning phase 4.
- Acoustic warning phase 4 (EURO NCAP only: After expiry of acoustic warning phase 3 and as from a speed of v ≥25 km/h a quiet acoustic warning is sounded for maximum t = 93 s at an interval of t = 0.5 s.
Cancellation of seat belt reminder warning:
- The last acoustic warning phase is fully completed.
- The belt was fitted during the active seat belt reminder warning.
- When the vehicle is stationary the vehicle door on the actuating side is opened.
Seat belt reminder warning reactivation
- Seat belt release has been detected again.
- If the vehicle is at a standstill and the driver or front passenger door is opened and then closed again
- Ignition sequence as from circuit 61 ON detected again.
Additional function requirements for exterior lighting (ABL) warning messages
^ Circuit 15 On (provided by EIS [EZS] control unit)
Exterior lighting (ABL) function sequence
The active high beams and turn signal light actuation is displayed by the indicator lamps in the instrument cluster. The "Active high beams actuation" feedback is indicated by the high beams indicator lamp (A1e3). The "Active turn signal light actuation" feedback is indicated by the left turn signal indicator lamp (A1e1) and the right turn signal indicator lamp (A1e2).
The high beams actuation status is sent by the driver SAM control unit (N10/10) over the interior CAN to the instrument cluster. The function of the exterior lights (ABL) components is permanently monitored.
If a fault is detected on a component, the monitoring control unit sends corresponding information over the interior CAN to the instrument cluster. The instrument cluster receives the data and then issues corresponding messages on the multifunction displays. The function of the components in the exterior lights is monitored by the following control units:
- Xenon headlamp control unit (E1n1)
- Xenon headlamp control unit (E2n1)
- Driver-side SAM control unit
- Right SAM control unit (N10/11)
- Rear SAM control unit (N10/8)
- Left door control unit (N69/1)
- Right door control unit (N69/2)
The xenon headlamp control units monitor the functions of the actuated components. If a xenon headlamp control unit detects a fault or a failure of the relevant component, it sends corresponding information to the diagnostic CAN (CAN D).
The central gateway control unit forwards this over the engine compartment CAN to the instrument cluster. The instrument cluster receives this data and then issues corresponding messages on the multifunction displays.
Additional functional requirements for tire pressure monitor control/warning messages (with code (470) Tire pressure monitor (standard))
^ Circuit 15 On (provided by EIS [EZS] control unit)
Function sequence for tire pressure monitor control/warning messages (with code (470) Tire pressure monitor (standard))
If the TPM [RDK] control unit (N88) detects a pressure loss at one of the tires or system faults, it sends corresponding information over the interior CAN to the instrument cluster. The instrument cluster receives the data and then issues corresponding messages on the multifunction displays.
Function sequence emergency call system indicator/warning messages (with code (359) TELE AID emergency call system)
If the emergency call system control unit (N123/4) detects a fault during a self-test or if the emergency call system is activated, corresponding messages are shown on the multifunction displays. The relevant information is sent by the emergency call system control unit to the diagnostic CAN. The central gateway control unit forwards this over the interior CAN to the instrument cluster.
Function sequence for memory adjustment control message (with code (494) USA version)
The instrument cluster outputs an acknowledgment tone when a memory position is stored.
To this end, the left front seat adjustment control unit with memory (N32/1) or the right front seat adjustment control unit with memory (N32/2) forward a corresponding request over the interior CAN to the instrument cluster.
Additional function requirements for Keyless-Go control/ warning messages
^ Circuit 15 On (provided by EIS [EZS] control unit)
Function sequence for Keyless-Go control/warning messages
If the KEYLESS-GO control unit (N69/5) does not detect a valid transmitter key (A8/1) during a start attempt or if the electronic selector lever module control unit (N15/5) does not send the selector lever position "P" or "N" status, then a chime is heard and corresponding messages are shown in the multifunction displays. The relevant information for this is sent by the KEYLESS-GO control unit over the interior CAN to the instrument cluster.
Additional function requirements for audio/communication/ navigation control messages
^ Circuit 15 On (provided by EIS [EZS] control unit)
Function sequence for audio/communication/navigation control messages
The multifunction displays show the information from the audio systems installed in the vehicle.
Depending on the equipment specification, additional navigation information or communication-relevant information (e.g. network provider, telephone book entries) is shown on the right multifunction display. The instrument cluster receives all the relevant information from the COMAND operating, display and controller unit (A40/3) over the interior CAN. The left multifunction display shows the corresponding menu and the right multifunction display the text and symbol-based information.
Additional function requirements for transmission-control control/warning messages
^ Circuit 15 On (provided by EIS [EZS] control unit)
Function sequence for transmission-control control/warning messages
The current gear range and the current transmission mode are shown in the right multifunction display. The gear range is shown on the left-hand edge and the transmission mode on the right-hand edge of the multifunction display.
The display shows the respective shift range or the selector lever position ("D" to "P"), and the selected transmission mode ("C", "S" or "M").
If the electronic transmission control (EGS) control unit (N15/3) detects malfunctions or faults in the transmission control, it sends corresponding information over the engine compartment CAN to the instrument cluster. The instrument cluster receives the data and then issues corresponding messages on the multifunction displays.
Additional function requirements for engine-control control/ warning messages
^ Circuit 15 On (provided by EIS [EZS] control unit)
Function sequence for engine-control control/warning messages
If there is a fault in the diesel fuel injection system, in the ignition system or in the exhaust system, the ME-SFI [ME] control unit sends corresponding information over the engine compartment CAN to the instrument cluster.
The instrument cluster receives the information, actuates the engine diagnostic indicator lamp (A1e58) (without code (494) USA version) or the CHECK ENGINE indicator lamp (A1e26) (with code (494) USA version) and forwards corresponding messages over the multifunction displays.
Additional function requirements for brake wear indicator
^ Circuit 15 On (provided by EIS [EZS] control unit)
Function sequence for brake wear indicator
The reaching of a wear limit for the front axle brake pads is detected by the right front brake pad contact sensor (S10/2) and the reaching of a wear limit for the rear axle brake pads is detected by the right rear brake pad contact sensor (S10/4). When the wear limit for the brake pads on the front axle is reached, the vehicle mass is switched through to the front passenger-side SAM control unit over the front brake pad contact sensor.
When the wear limit for the brake pads on the rear axle is reached, the vehicle mass is switched through to the rear passenger-side SAM control unit over the rear brake pad contact sensor. The corresponding front SAM control unit then sends a signal over the interior CAN to the instrument cluster. The instrument cluster receives this signal and issues a corresponding message over the multifunction displays.
Additional function requirements for brake fluid level warning message
^ Circuit 15 On (provided by EIS [EZS] control unit)
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 driver SAM control unit.
If the fluid level is too low the driver SAM control unit sends a corresponding signal over the interior CAN to the instrument cluster.
The instrument cluster receives this signal, actuates the brake fluid and parking brake warning lamp (A1e7) and issues a corresponding message on the multifunction displays.
Additional function requirements for lights on reminder
^ Circuit 15C OFF (provided by EIS [EZS] control unit)
^ Circuit 58 ON
Lights on reminder warning function sequence
If at circuit 15C OFF and with the standing lights switched off, the driver door is opened, the instrument cluster actuates the warning buzzer and issues a corresponding message over the multifunction displays. The active standing lights actuation is sent by the driver SAM control unit and the status of the driver door by the rear SAM control unit to the interior CAN.
If the transmitter key is removed from the EIS [EZS] control unit when the rear fog lamp actuation is active, and then the driver door is opened, the instrument cluster actuates the warning buzzer and issues a corresponding message on the multifunction displays.
Additional function requirements for parking brake on reminder warning
^ Vehicle speed v > 5 km/h (calculated by instrument cluster)
Parking brake warning function sequence
The status of the parking brake is monitored by the parking brake inspection switch (S12). If the parking brake inspection switch is actuated at a speed of v > 5 km/h, the instrument cluster actuates the brake fluid and parking brake warning lamp and the warning buzzer. If the vehicle speed drops to less than v = 2.5 km/h, the instrument cluster stops actuating the warning buzzer. The status of the parking brake indicator switch is read in directly by the driver-side SAM control unit and sent to the interior CAN.
Additional function requirements for engine oil level warning message
^ Circuit 15 On (provided by EIS [EZS] control unit)
^ Circuit 61 OFF (signal generated by ME-SFI [ME] control unit)
Function sequence for engine oil level warning message
To monitor the engine oil level, an oil sensor has been installed (oil level, temperature and quality) (B40).
The oil sensor data are read in directly by the ME-SFI [ME] control unit and evaluated. If necessary, the ME-SFI [ME] control unit sends a corresponding signal over the engine compartment CAN to the instrument cluster. The instrument cluster receives the data and then issues corresponding messages on the multifunction displays. The following messages are issued on the right multifunction display:
- "At refueling stop, top up with 1l of engine oil"
- "Stop vehicle. Engine oil level. Engine OFF"
- "Engine oil level, reduce oil level"
- "Engine oil level. Measurement of engine oil level not possible"
Additional function requirements for coolant and coolant temperature warning messages
^ Circuit 15 On (provided by EIS [EZS] control unit)
Function sequence for coolant and coolant temperature warning messages
The coolant level in the expansion reservoir is monitored by the coolant level indicator switch (S41).
If the coolant level is too low the front-passenger SAM control unit sends a corresponding signal over the interior CAN to the instrument cluster. The instrument cluster receives this signal and issues a corresponding message over the multifunction displays.
The coolant temperature is recorded by the coolant temperature sensor (B11/4). The ME-SFI [ME] control unit reads in the signal of the coolant temperature sensor, uses it to calculate the coolant temperature and then sends the corresponding temperature value over the engine compartment CAN to the instrument cluster.
When a coolant temperature of T > 130 °C is reached, the instrument cluster actuates the coolant temperature warning lamp (A1e54) and issues a corresponding message on the multifunction displays.
Additional function requirements for windshield washer system fluid level warning message
^ Circuit 15 On (provided by EIS [EZS] control unit)
Function sequence for windshield washer system fluid level warning message
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-passenger SAM control unit. If the level is too low the front-passenger SAM control unit sends a corresponding signal over the interior CAN to the instrument cluster. The instrument cluster receives this signal and issues a corresponding message over the multifunction displays.
Turn signal confirmation function sequence
Acoustic feedback about the active turn signal light actuation is realized by the acoustic turn signal indicator integrated into the instrument cluster.
Visual feedback is indicated by the turn signal indicator lamps.
Additional function requirements for tank cap open warning message (with code (494) USA version)
^ Vehicle speed v > 5 km/h (calculated by instrument cluster)
Tank cap open warning message function sequence (with code (494) USA version)
The ME-SFI [ME] control unit monitors the status of the tank cap. If, after starting a journey, an open tank cap is detected, the CDI control unit or the ME-SFI [ME] control unit issues a corresponding signal over the engine compartment CAN to the instrument cluster. The instrument cluster receives this signal, actuates the fuel reserve warning lamp (A1e4) so it blinks at a frequency of f = 2.5 Hz and shows a corresponding message on the multifunction displays.
