2019 MERCEDES-BENZ SLC ECU

Display messagesPossible causes/consequences andPPSolutions
The yellow$warning lamp and the redI(USA only) or$(Canada only) indicator lamp light up.
The electric parking brake is malfunctioning.
To release:
XSwitch off the ignition and turn it back on.
XRelease the electric parking brake manually.
or
XRelease the electric parking brake automatically (Ypage 135).
If the electric parking brake still cannot be released:
XDo not drive on.
XConsult a qualified specialist workshop.
The redI(USA only) or$(Canada only) indicator lampflashes and the yellow$warning lamp lights up.
The electric parking brake is malfunctioning.
To release:
XSwitch off the ignition and turn it back on.
XRelease the electric parking brake manually.
To apply:
XSwitch off the ignition and turn it back on.
XApply the electric parking brake manually.
If the redI(USA only) or$(Canada only) indicator lampcontinues to flash:
XDo not drive on.
XSecure the vehicle against rolling away (Ypage 289).
XShift the transmission to position].
XTurn the front wheels towards the curb.
XConsult a qualified specialist workshop.
186Displaymessages
On-b oard computer and displays

Display messagesPossible causes/consequences andPPSolutions
The yellow$warning lamp lights up and the redI(USAonly) or$(Canada only) indicator lamp flashes.
It is not possible to apply the electric parking brake manually.
XShift the transmission to position].
XVisit a qualified specialist workshop.
'(USA only)
M(Canada only)
Check Brake FluidCheck Brake FluidLevelLevel
There is not enough brake fluid in the brake fluid reservoir.
In addition, the'(USA only) orM(Canada only) warninglamp lights up in the instrument cluster and a warning tone sounds.
GWARNING
The braking effect may be impaired.
There is a risk of an accident.
XPull over and stop the vehicle safely as soon as possible, payingattention to road and traffic conditions. Do not continue drivingunder any circumstances.
XSecure the vehicle against rolling away (Ypage 134).
XConsult a qualified specialist workshop.
XDo not add brake fluid. This does not correct the malfunction.
&
Check Brake PadCheck Brake PadWearWear
The brake pads/linings have reached their wear limit.
XVisit a qualified specialist workshop.
PRE-SAFE Inopera‐PRE-SAFE Inopera‐tive See Opera‐tive See Opera‐tor's Manualtor's Manual
Important functions of PRE-SAFE®have failed. All other occupantsafety systems, e.g. air bags, remain available.
XVisit a qualified specialist workshop immediately.
Active BrakeActive BrakeAssist FunctionsAssist FunctionsCurrently LimitedCurrently LimitedSee Operator's Man‐See Operator's Man‐ualual
Active Brake Assist is temporarily inoperative.
Possible causes are:
Rthe radar sensor system is temporarily inoperative, e.g. due toelectromagnetic radiation emitted by nearby TV or radio stationsor other sources of electromagnetic radiation
Rthe system is outside the operating temperature range
Rthe on-board voltage is too low
When the causes stated above no longer apply, the display messagedisappears.
Active Brake Assist is operational again.
If the display message does not disappear:
XPull over and stop the vehicle safely as soon as possible, payingattention to road and traffic conditions.
XSecure the vehicle against rolling away (Ypage 134).
XRestart the engine.
188Displaymessages
On-b oard computer and displays

Display messagesPossible causes/consequences andPPSolutions
Active BrakeActive BrakeAssist FunctionsAssist FunctionsLimited See Opera‐Limited See Opera‐tor's Manualtor's Manual
Active Brake Assist is unavailable due to a malfunction.
XVisit a qualified specialist workshop.
Radar SensorsRadar SensorsDirty See Opera‐Dirty See Opera‐tor's Manualtor's Manual
The radar sensor system is malfunctioning.
Possible causes are:
Rdirt on sensors
Rheavy rain or snow
Rwhen driving on inter-urban roads without traffic or infrastructure,e.g. in desert-like areas
At least one driving system or driving safety system is malfunction-ing or is temporarily unavailable:
RActive Brake Assist
RActive Distance Assist DISTRONIC
Once the cause of the problem is no longer present, the driving anddrive safety systems will be available again. The display messagedisappears.
If the display message does not disappear:
XPull over and stop the vehicle safely as soon as possible, payingattention to road and traffic conditions.
XSecure the vehicle against rolling away (Ypage 134).
XSwitch off the engine.
XClean all sensors (Ypage 250).
XRestart the engine.The display message disappears.
u
SRS MalfunctionSRS MalfunctionService RequiredService Required
The restraint system is malfunctioning. Theuwarning lamp alsolights up in the instrument cluster.
GWARNING
The air bags or Emergency Tensioning Devices may either be trig-gered unintentionally or, in the event of an accident, may not betriggered.
There is an increased risk of injury.
XVisit a qualified specialist workshop immediately.
Further information about the restraint system (Ypage 39).
Displaymessages189
On-b oard computer and displays
Z

Display messagesPossible causes/consequences andPPSolutions
Front-passengerFront-passengerAir Bag DisabledAir Bag DisabledSee Operator's Man‐See Operator's Man‐ualual
The front-passenger front air bag and front-passenger knee air bagare disabled during the journey, although:
Ran adult
or
Ra person of the corresponding stature is on the front-passengerseat
If additional forces are applied to the seat, the system may interpretthe occupant's weight as lower than it actually is.
GWARNING
The front-passenger front air bag and front-passenger knee air bagmay not be triggered in the event of an accident.
There is an increased risk of injury.
XPull over and stop the vehicle safely as soon as possible, payingattention to road and traffic conditions.
XSecure the vehicle against rolling away (Ypage 134).
XSwitch the ignition off.
XHave the occupant on the front-passenger seat get out of thevehicle.
XKeep the seat unoccupied, close the front-passenger door andswitch on the ignition.
XObserve the PASSENGER AIR BAG indicator lamps in the centerconsole and the multifunction display and check the following:
Seat unoccupied and ignition switched on:
Ra self-diagnosis is carried out. The PASSENGER AIR BAG OFFand PASSENGER AIR BAG ON indicator lamps must light upsimultaneously for approximately six seconds.
Rthe PASSENGER AIR BAG OFF indicator lamp must then lightup and remain lit after the self-diagnosis. If the indicator lampis on, OCS has disabled the front-passenger front air bag andfront-passenger knee bag (Ypage 46)
RtheFront-passenger Air Bag Enabled See Operator'sFront-passenger Air Bag Enabled See Operator'sManualManualorFront-passenger Air Bag Disabled See Oper‐Front-passenger Air Bag Disabled See Oper‐ator's Manualator's Manualdisplay messages must not appear in the mul-tifunction display
XWait for a period of at least 60 seconds until the necessary sys-tem checks have been completed.
XMake sure that the display messages do not appear in the multi-function display.
If these conditions are fulfilled, the front-passenger seat can beoccupied again. Whether the PASSENGER AIR BAG OFF or ON indi-cator lamp remains lit or goes out depends on how OCS classifiesthe occupant.
If the conditions are not fulfilled, the system is not operating cor-rectly.
XVisit a qualified specialist workshop immediately.
Observe the additional information on OCS (Ypage 46).
Displaymessages191
On-b oard computer and displays
Z

Display messagesPossible causes/consequences andPPSolutions
Front-passengerFront-passengerAir Bag EnabledAir Bag EnabledSee Operator's Man‐See Operator's Man‐ualual
The front-passenger front air bag and front-passenger knee air bagare enabled during the journey, although:
Ra child, a small adult or an object weighing less than the system'sweight threshold is located on the front-passenger seat
or
Rthe front-passenger seat is unoccupied
The system may detect objects or forces applying additional weighton the seat.
GWARNING
The front-passenger front air bag and the front-passenger knee bagmay be deployed unintentionally.
There is an increased risk of injury.
XPull over and stop the vehicle safely as soon as possible, payingattention to road and traffic conditions.
XSecure the vehicle against rolling away (Ypage 134).
XSwitch the ignition off.
XOpen the front-passenger door.
XRemove the child and the child restraint system from the front-passenger seat.
XMake sure that there are no objects on the seat adding to theweight.The system might otherwise detect the additional weight andinterpret the seat occupant's weight as greater than it actually is.
XKeep the seat unoccupied, close the front-passenger door andswitch on the ignition.
XObserve the PASSENGER AIR BAG indicator lamps in the centerconsole and the multifunction display and check the following:
Seat unoccupied and ignition switched on:
Ra self-diagnosis is carried out. The PASSENGER AIR BAG OFFand PASSENGER AIR BAG ON indicator lamps must light upsimultaneously for approximately six seconds.
Rthe PASSENGER AIR BAG OFF indicator lamp must then lightup and remain lit after the self-diagnosis. If the indicator lampis on, OCS (Occupant Classification System) has disabled thefront-passenger front air bag and front-passenger knee air bag(Ypage 46)
RtheFront-passenger Air Bag Enabled See Operator'sFront-passenger Air Bag Enabled See Operator'sManualManualorFront-passenger Air Bag Disabled See Oper‐Front-passenger Air Bag Disabled See Oper‐ator's Manualator's Manualdisplay messages must not appear in the mul-tifunction display
XWait for a period of at least 60 seconds until the necessary sys-tem checks have been completed.
XMake sure that the display messages do not appear in the multi-function display.
If these conditions are fulfilled, the front-passenger seat can beoccupied again. Whether the PASSENGER AIR BAG OFF or ON indi-
192Displaymessages
On-b oard computer and displays

Display messagesPossible causes/consequences andPPSolutions
=
Stop Vehicle SeeStop Vehicle SeeOperator's ManualOperator's Manual
The battery is no longer being charged and the condition of chargeis too low.
A warning tone also sounds.
XPull over and stop the vehicle safely and switch off the engine,paying attention to road and traffic conditions.
XSecure the vehicle against rolling away (Ypage 134).
XObserve the instructions in the=See Operator's ManualSee Operator's Manualdisplay message.
XConsult a qualified specialist workshop.

Display messagesPossible causes/consequences andPPSolutions
Lane KeepingLane KeepingAssist CurrentlyAssist CurrentlyUnavailable SeeUnavailable SeeOperator's ManualOperator's Manual
Lane Keeping Assist is deactivated and temporarily inoperative.
Possible causes are:
Rthe windshield in the camera's field of vision is dirty
Rvisibility is impaired due to heavy rain, snow or fog
Rthere have been no lane markings for an extended period
Rthe lane markings are worn away, dark or covered up, e.g. by dirtor snow
When the causes stated above no longer apply, the display messagedisappears.
Lane Keeping Assist is operational again.
If the display message does not disappear:
XPull over and stop the vehicle safely as soon as possible, payingattention to road and traffic conditions.
XSecure the vehicle against rolling away (Ypage 134).
XClean the windshield.
Lane KeepingLane KeepingAssist InoperativeAssist InoperativeLane Keeping Assist is faulty.
XVisit a qualified specialist workshop.
Blind Spot AssistBlind Spot AssistCurrently Unavaila‐Currently Unavaila‐ble See Operator'sble See Operator'sManualManual
Blind Spot Assist is temporarily inoperative.
Possible causes are:
Rfunction is impaired due to heavy rain or snow
Rthe radar sensor system is outside the operating temperaturerange
Rthe radar sensor system is temporarily inoperative, e.g. due toelectromagnetic radiation emitted by nearby TV or radio stationsor other sources of electromagnetic radiation
The yellowcindicator lamps also light up in the exterior mirrors.
When the causes stated above no longer apply, the display messagedisappears.
Blind Spot Assist is operational again.
If the display message does not disappear:
XPull over and stop the vehicle safely as soon as possible, payingattention to road and traffic conditions.
XSecure the vehicle against rolling away (Ypage 134).
XClean the sensors (Ypage 250).
XRestart the engine.
Blind Spot AssistBlind Spot AssistInoperativeInoperativeBlind Spot Assist is malfunctioning.
The yellowcindicator lamps also light up in the exterior mirrors.
XVisit a qualified specialist workshop.
198Displaymessages
On-b oard computer and displays

Display messagesPossible causes/consequences andPPSolutions
Active DistanceActive DistanceAssist CurrentlyAssist CurrentlyUnavailable SeeUnavailable SeeOperator's ManualOperator's Manual
Active Distance Assist DISTRONIC is temporarily inoperative.
Possible causes are:
Rthe radar sensor system is temporarily inoperative, e.g. due toelectromagnetic radiation emitted by nearby TV or radio stationsor other sources of electromagnetic radiation
Rthe system is outside the operating temperature range
Rthe on-board voltage is too low
A warning tone also sounds.
When the causes stated above no longer apply, the display messagedisappears.
Active Distance Assist DISTRONIC is operational again.
If the display message does not disappear:
XPull over and stop the vehicle safely as soon as possible, payingattention to road and traffic conditions.
XSecure the vehicle against rolling away (Ypage 134).
XRestart the engine.
Active DistanceActive DistanceAssist InoperativeAssist InoperativeActive Distance Assist DISTRONIC is faulty.
A warning tone also sounds.
XVisit a qualified specialist workshop.
Act. DistanceAct. DistanceAssist SuspendedAssist SuspendedYou have depressed the accelerator pedal. Active Distance AssistDISTRONIC is no longer controlling the speed of the vehicle.
XRemove your foot from the accelerator pedal.
Distance Assist--Distance Assist--- mph- mphA condition for activating Active Distance Assist DISTRONIC has notbeen met.
XCheck the activation conditions for Active Distance AssistDISTRONIC (Ypage 144).
Cruise Control OffCruise Control OffCruise control has been deactivated.
If a warning tone also sounds, cruise control has deactivated auto-matically (Ypage 142).
Cruise Control - -Cruise Control - -- mph- mphCruise control cannot be activated, since not all of the activationconditions have been met.
XCheck the activation conditions for cruise control (Ypage 142).
Cruise ControlCruise ControlInoperativeInoperativeCruise control is malfunctioning.
A warning tone also sounds.
XVisit a qualified specialist workshop.
200Display messages
On-board computer and displays