Activate antitheft alarm system, function

Function requirements, general

 Circuit 15C OFF

Activate antitheft alarm system (ATA [ATA]), general

The ATA is automatically activated with the central locking (CL) when the vehicle is locked. Then the individual alarm inputs are monitored. The activated ATA [ATA] is indicated by the ATA [ATA] function indicator (N72/1e3) permanently flashing in the upper control panel control unit (N72/1). The front SAM control unit (N10/6) actuates the ATA [ATA] function indicator via the instrument panel LIN (LIN1).

 On vehicles for Belgium, the ATA arms automatically without locking the vehicle with the CL.

 Model 205, 253
with code 551 (Anti-theft warning system)
with code 852 (Sensor system for anti-theft alarm system (ATA))
Model 205, 253
with code 551 (Anti-theft warning system)
with code 882 (Interior protection and tow-away protection)
Before locking the CL, the tow-away protection or interior protection can be activated or deactivated via a menu in the head unit (A26/17).

 Model 205, 253
with code 362 (HERMES LTE)
with code 551 (Anti-theft warning system)
with code 852 (Sensor system for anti-theft alarm system (ATA))
Model 205, 253
with code 362 (HERMES LTE)
with code 551 (Anti-theft warning system)
with code 882 (Interior protection and tow-away protection)
When the corresponding service is activated, tow-away protection (and parking damage detection) or interior protection can be activated or deactivated via the customer's mobile phone.

Activation of the ATA comprises the following partial functions:

 Function sequence for activating ATA [ATA]

 Function sequence for switching off tow-away protection and parking damage detection of the ATA (with code 852 (Sensor system for anti-theft alarm system) or with code 882 (Interior protection and tow-away protection))

 Function sequence for switching off interior protection of the anti-theft alarm system (with code 852 (Sensor system for anti-theft alarm system) or with code 882 (Interior protection and tow-away protection))

 Function sequence for activating alarm inputs

Function sequence for activating ATA [ATA]

The ATA is activated when the CL is locked. The electronic ignition lock control unit (N73) transmits the status of the CL via the interior CAN (CAN B) to the front SAM control unit and to the overhead control panel control unit (N70) (model 205 as of June 1, 2018, model 253 (except model 253.99) as of June 1, 2019, model 253.99 with code 882 (Interior protection and tow-away protection)), to the ATA/tow-away protection/interior protection control unit (N26/6) (model 205.0/1/2/3 up to May 31, 2018 or model 253 (except model 253.99) up to May 31, 2019 with code 882 (Interior protection and tow-away protection)) or to the ATA/tow-away protection/interior protection control unit (N26/3) (model 205.4 up to May 31, 2018 with code 882 (Interior protection and tow-away protection)). Then the ATA is activated.

 Special case driver door: If the driver door is still open when the CL is locked, it is not locked. After closing the driver door, the left front door control unit (N69/1) sends the status of the driver door via interior CAN to the front SAM control unit. The alarm input is included in the polling cycle. This leads to actuation of an alarm when opening the driver door without previous deactivation of the ATA [ATA].

 Automatic activation (only vehicles for Belgium): If the driver's door, trunk lid or tailgate is opened and closed again after the transmitter key has been removed from the electronic ignition latch control unit, an automatic activation of the ATA takes place t = 100 100s after the closing of the last door, trunk lid or the tailgate regardless of the vehicle locking

Additional function requirements for switching off tow-away protection and parking damage detection of the anti-theft alarm system (with code 852 (Sensor system for anti-theft alarm system) or with code 882 (Interior protection and tow-away protection))

 ATA [ATA] not yet activated

Function sequence for switching off tow-away protection and parking damage detection of the ATA (with code 852 (Sensor system for anti-theft alarm system) or with code 882 (Interior protection and tow-away protection))

The tow-away protection is deactivated via a menu in the head unit before locking the vehicle via the CL [ZV]. When tow-away protection is de-selected, parking damage detection (with code 852 (sensor system for anti-theft alarm system (ATA)) or with code 882 (interior protection and tow-away protection) in model 205 (except model 205.4) as of June 1, 2018 or in model 253 (except model 253.99) as of June 1, 2019 or in model 253.99) is deactivated. Operation takes place via the Audio/COMAND control panel (A40/9) (without code 446 (touchpad only)) or the touchpad (A105) (with code 446 (touchpad only)) and is shown in the Audio/COMAND display (A40/8).

The head unit reads in the signals of the Audio/COMAND control panel (without code 446 (touchpad only)) or of the touchpad (with code 446 (touchpad only)) via telematics CAN (CAN A) and transmits the request to deactivate tow-away protection via the user interface CAN (CAN HMI), electronic ignition lock control unit and interior CAN to the overhead control panel control unit (model 205 as of June 1, 2018, model 253 (except model 253.99) as of June 1, 2019, model 253.99) or to the ATA/tow-away protection/interior protection control unit (model 205 up to May 31, 2018 or model 253 (except model 253.99) up to May 31, 2019).

The overhead control panel control unit (model 205 as of June 1, 2018, model 253 (except model 253.99) as of June 1, 2019, model 253.99) or the ATA/tow-away protection/interior protection control unit (model 205 up to May 31, 2018 or model 253 (except model 253.99) up to May 31, 2019) deactivates the tow-away protection for the subsequent activation of the ATA and transmits, for the status display, a signal via:

 Interior CAN, electronic ignition latch control unit and user interface CAN to the instrument cluster (A1).

 Interior CAN, electronic ignition latch control unit and user interface CAN to the head unit. The head unit generates the corresponding image data and sends a switch-on request to the Audio/COMAND display via telematics CAN. The image data is sent via the LVDS line to the Audio/COMAND display.

Additional function requirements for switching off interior protection of the ATA (with code 852 (Sensor system for anti-theft alarm system) or with code 882 (Interior protection and tow-away protection))

 ATA [ATA] not yet activated

Function sequence for switching off interior protection of the anti-theft alarm system (with code 852 (Sensor system for anti-theft alarm system) or with code 882 (Interior protection and tow-away protection))

The interior protection is deactivated via a menu in the head unit before locking the vehicle via the CL [ZV]. Operation takes place via the Audio/COMAND control panel (without code 446 (touchpad only)) or the touchpad (with code 446 (touchpad only)) and is shown in the Audio/COMAND display.

The head unit reads in the signals of the Audio/COMAND control panel (without code 446 (touchpad only)) or of the touchpad (with code 446 (touchpad only)) via telematics CAN (CAN A) and transmits the request to deactivate interior protection via the user interface CAN (CAN HMI), electronic ignition lock control unit and interior CAN to the overhead control panel control unit (model 205 as of June 1, 2018, model 253 (except model 253.99) as of June 1, 2019, model 253.99) or to the ATA/tow-away protection/interior protection control unit (model 205 up to May 31, 2018 or model 253 (except model 253.99) up to May 31, 2019).

The overhead control panel control unit (model 205 as of June 1, 2018, model 253 (except model 253.99) as of June 1, 2019, model 253.99) or the ATA/tow-away protection/interior protection control unit (model 205 up to May 31, 2018 or model 253 (except model 253.99) up to May 31, 2019) deactivates the interior protection for the subsequent activation of the ATA and transmits, for the status display, a signal via:

 Interior CAN, electronic ignition latch control unit and user interface CAN to the instrument cluster.

 Interior CAN, electronic ignition latch control unit and user interface CAN to the head unit. The head unit generates the corresponding image data and sends a switch-on request to the Audio/COMAND display via telematics CAN. The image data is sent via the LVDS line to the Audio/COMAND display.

Additional function requirements for activating alarm inputs

 ATA [ATA] activated

Function sequence for activating alarm inputs

Activating alarm input function comprises the following subfunctions:

 Function sequence for monitoring switch

 Function sequence for activating tow-away protection and parking damage detection (with code 852 (Sensor system for anti-theft alarm system) or with code 882 (Interior protection and tow-away protection))

 Function sequence for activating interior protection (with code 852 (Sensor system for anti-theft alarm system) or with code 882 (Interior protection and tow-away protection))

 Function sequence for activating alarm siren (H3/1) (with code 882 (Interior protection and tow-away protection))

Function sequence for monitoring switch

The status (open or closed) of the following switched is checked cyclically every t = 200  ms:

 Left front door rotary tumbler switch (A85s1) in left front door latch (A85)

 Right front door rotary tumbler switch (A85/1s1) in right front door latch (A85/1)

 Left rear door rotary tumbler switch (A85/3s1) (model 205.0/1/2, 253) in door latch for left rear door (A85/3) (model 205.0/1/2, 253)

 Right rear door rotary tumbler switch (A85/4s1) (model 205.0/1/2, 253) in door latch for right rear door (A85/4) (model 205.0/1/2, 253)

 Trunk lid/liftgate latch main catch switch (A85/5s1) in trunk lid/liftgate latch (A85/5)

 Center console anti-theft alarm system switch group (S21) (model 205.4)

 Hood contact switch on driver's side (S62/43)

The left front door control unit reads in the status of the left front door rotary tumbler switch directly and sends it via interior CAN to the front SAM control unit. The right front door control unit (N69/2) reads in the status of the right front door rotary tumbler switch directly and sends this via interior CAN to the front SAM control unit.

The rear SAM control unit (N10/8) reads in the status of the trunk lid/liftgate latch main catch switch directly and sends this via interior CAN to the front SAM control unit.

Model 205.0/1/2, 253:

The left rear door control unit (N69/3) reads in the status of the left rear door rotary tumbler switch directly and sends this via interior CAN to the front SAM control unit. The right rear door control unit (N69/4) reads in the status of the right rear door rotary tumbler switch directly and sends this via interior CAN to the front SAM control unit.

The front SAM control unit directly reads in the status of the center console anti-theft alarm system switch group (model 205.4) and the driver's side hood contact switch and evaluates the status of all other alarm inputs.

Alarm inputs that are only subsequently set to idle state (if e.g. the trunk lid or the tailgate is only closed after vehicle locking) are also armed t = 10 s after closing.

Function sequence for activating tow-away protection and parking damage detection (with code 852 (Sensor system for anti-theft alarm system) or with code 882 (Interior protection and tow-away protection))

The tow-away protection and the parking damage detection (with code 852 (sensor system for anti-theft alarm system (ATA)) or with code 882 (interior protection and tow-away protection) in model 205 (except model 205.4) as of June 1, 2018 or in model 253 (except 253.99) as of June 1, 2019 or in model 253.99) are activated (if not previously de-selected for the next locking) t = 60 s after the central locking is locked and the last door, the trunk lid or the liftgate is closed.

For the tow-away protection, the inclination sensor in the overhead control panel control unit (model 205 as of June 1, 2018, model 253 (except model 253.99) as of June 1, 2019, model 253.99) or in the ATA/tow-away protection/interior protection control unit (model 205 up to May 31, 2018 or model 253 (except model 253.99) up to May 31, 2019) determines a reference position, against which the relative vehicle inclination is then compared during the active time. Determination of this reference position takes approx. t = 10 to 15 s. Therefore an alarm can only be triggered approx. t = 60 s after the ATA is activated, at the earliest.

When the maximum vehicle inclination is exceeded with regard to the reference position, an alarm is triggered.  If the vehicle inclination changes very slowly (e.g. leaky tire), the reference position adapts to the current vehicle position to prevent inadvertent activation of the inclination sensor.

For parking damage detection, the vehicle movement is evaluated via the inclination sensor. If a physical shock that may have caused parking damage is detected, a corresponding message is sent.

If the inclination sensor is faulty, all other components of the ATA remain operable and the relevant fault codes are entered in the fault memory of the overhead control panel control unit (model 205 as of June 1, 2018, model 253 (except model 253.99) as of June 1, 2019, model 253.99) or of the ATA/tow-away protection/interior protection control unit (model 205 up to May 31, 2018 or model 253 (except model 253.99) up to May 31, 2019).

Function sequence for activating interior protection (with code 852 (Sensor system for anti-theft alarm system) or with code 882 (Interior protection and tow-away protection))

The interior protection is (if not previously deselected for the next locking) only activated t = 10 s after the locking of the CL and the closing of the last door and trunk lid or the tailgate. After a further t = 10 s, is the interior protection is ready to issue an alarm as the overhead control panel control unit (model 205 as of June 1, 2018, model 253 (except model 253.99) as of June 1, 2019, model 253.99) or the ATA/tow-away protection/interior protection control unit (model 205 up to May 31, 2018 or model 253 (except model 253.99) up to May 31, 2019) must first of all calibrate itself to the vehicle interior.

On model 205.2, 253, the signals of the following sensors are evaluated in addition to the interior protection:

 Left rear window glass breakage sensor (B39)

 Right rear window glass breakage sensor (B39/1)

 Rear window glass breakage sensor (B39/4)

The status of the glass breakage sensors is read in directly by the overhead control panel control unit (model 205 as of June 1, 2018, model 253 (except model 253.99) as of June 1, 2019, model 253.99) or from the ATA/tow-away protection/interior protection control unit (model 205 up to May 31, 2018 or model 253 (except model 253.99) up to May 31, 2019).

If a defect is detected, the remaining ATA functions are still ensured regardless of this error. The corresponding fault codes are entered in the fault memory of the overhead control panel control unit (model 205 as of June 1, 2018, model 253 (except model 253.99) as of June 1, 2019, model 253.99) or of the ATA/tow-away protection/interior protection control unit (model 205 up to May 31, 2018 or model 253 (except model 253.99) up to May 31, 2019).

Function sequence for activating alarm siren (with code 882 (Interior protection and tow-away protection))

The alarm siren is armed together with the ATA and cyclically addressed approx. every t = 600 ms by the overhead control panel control unit (model 205 as of June 1, 2018, model 253 (except model 253.99) as of June 1, 2019, model 253.99) or by the ATA/tow-away protection/interior protection control unit (model 205 up to May 31, 2018 or model 253 (except model 253.99) up to May 31, 2019) via alarm systems LIN (LIN B14).

 Deactivate ATA [ATA]: A complete deactivation of the ATA occurs by opening the CL with the transmitter key via radio or by inserting the transmitter key in the electronic ignition latch control unit or by actuating the KEYLESS-GO start/stop button (S2/3) (with CODE 889 (KEYLESS-GO) or CODE 893 (KEYLESS-GO start function)). The electronic ignition latch control unit sends the corresponding signal via interior CAN to the front SAM control unit, which then deactivates the ATA [ATA].