Activate antitheft alarm system, function

Function requirements, general

 Circuit 15C OFF

 Central locking operating properly

Activate antitheft alarm system (ATA [EDW]), 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 [EDW] is indicated by the ATA [EDW] function indicator (N721e2) permanently flashing in the upper control panel control unit (N721). For this purpose the front SAM control unit with fuse and relay module (N10/1) transmits a signal to the upper control panel control unit via the instrument panel LIN (LIN 1).

 Before locking the CL, the tow-away protection (with code 882 (Interior monitoring)) or interior protection (with code 882 (Interior monitoring)) can be deactivated.

Activating the ATA comprises the following partial functions:

 Function sequence for activating ATA [EDW]

 Function sequence for switching off tow-away protection of ATA

(with code 882 (Interior monitoring))

 Function sequence for switching off interior protection of ATA

(with code 882 (Interior monitoring))

 Function sequence for activating alarm inputs

Function sequence for activating ATA [EDW]

Activation of the ATA [EDW] comprises the following subfunctions:

 Function sequence for locking CL with transmitter key (A8/1)

 Function sequence for locking CL with automatic relocking feature

 Function sequence for locking CL with KEYLESS-GO

(with code 889 (KEYLESS-GO))

 Special case: Driver door:

If the driver door is still open when the CL is locked, it is not locked. When the driver door is closed, the door status is indicated to the rear SAM control unit with fuse and relay module (N10/2) and the alarm input is included in the checking cycle. This leads to actuation of an alarm when opening the driver door without previous deactivation of the ATA [EDW].

Function sequence for locking CL with transmitter key

When the lock button on the transmitter key is actuated, it transmits a radio signal to the rear SAM control unit with the FM, AM and CL antenna amplifier (A2/18). This transmits the signal to the electronic ignition lock control unit (N73) via the interior CAN. Parallel to the radio signals (as of 01.06.2015 not with code 889 (KEYLESS-GO)) the transmitter key transmits an infrared signal to the driver door infrared remote control receiver (A26/1) (precise aiming required). This signals is read in by the left door control unit (N69/1) and transmitted to the electronic ignition lock control unit via the interior CAN.

The access authorization code of the transmitter key is checked in both cases by the electronic ignition lock control unit.

If the access authorization is valid, the message "Vehicle locked" is transmitted with the interior CAN to the rear SAM control unit, which then activates the ATA.

 Detailed information on the function sequence for locking the CL, is given in a separate document.

Function sequence for locking CL with automatic relocking feature

The automatic relocking function is actuated by the electronic ignition lock control unit. If the vehicle is unlocked and neither a door nor the trunk lid is opened within 40 s, the vehicle relocks automatically. The electronic ignition switch control unit transmits with interior CAN the message "Vehicle locked" to the rear SAM control unit, which then activates the ATA.

 Detailed information on the function sequence for locking the CL, is given in a separate document.

Function sequence for locking CL with KEYLESS-GO (with code (889) KEYLESS-GO)

 Detailed information on function sequence for locking CL is described elsewhere.

After locking the CL, the electronic ignition switch control unit transmits the message "Vehicle locked" with interior CAN to the rear SAM control unit, which then activates the ATA.

Additional function requirements for deactivating ATA tow-away protection (with CODE 882 (Interior monitoring))

 ATA [EDW] not yet activated

Function sequence for deactivation of ATA tow-away protection (with CODE 882 (Interior monitoring))

The signals from the two-away protection button (S93/3s1) are read in by the overhead control panel control unit (N70) and relayed via the wiper/inside rearview mirror LIN (LIN 2) to the front SAM control unit.

The front SAM control unit relays the signal to the rear SAM control unit via the interior CAN. It deactivates the tow-away protection for the following activation of the ATA [EDW].

Simultaneously the rear SAM control unit transmits the status of the ATA via rear SAM LIN (LIN B4) to the interior protection sensor (A26/13) and front SAM control unit via the interior CAN.

Deselection of the tow-away protection is confirmed by an LED in the tow-away protection button for approx. t = 2 s after releasing the tow-away protection button.

Additional function requirements for deactivating ATA interior protection (with CODE 882 (Interior monitoring))

 ATA [EDW] not yet activated

Function sequence for deactivation of ATA interior protection (with CODE 882 (Interior monitoring))

The signals from the interior protection button (S93/3s3) are read in by the overhead control panel control unit and relayed to the front SAM control unit via the wiper/inside rearview mirror LIN.

The front SAM control unit relays the signal to the rear SAM control unit via the interior CAN. It deactivates the interior protection for the following activation of the ATA [EDW].

Simultaneously the rear SAM control unit transmits the ATA status via the rear SAM-LIN to the interior protection sensor and front SAM control via the interior CAN.

Deselection of the interior protection is confirmed by an LED flashing in the interior protection button at f = 6.25 Hz (t = 80 ms ON, t = 80 ms OFF) for approx. t = 2 s.

Additional function requirements for activating alarm inputs

 ATA [EDW] 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

(with code 882 (Interior monitoring))

 Function sequence for activating interior protection

(with code 882 (Interior monitoring))

 Function sequence for activating the alarm siren (H3/1)

(without code 494 (USA version))

Function sequence for monitoring switch

The status of the following switches is checked cyclically every t = 200 ms. If the polls indicate that an input is at rest within t = 10 s, the corresponding input is then armed.

Alarm inputs set later to the non-actuated state, e.g. if the trunk lid is closed only after the vehicle has been locked, are also armed t = 10 s after closing.

Monitored switches:

 Pedestrian protection Hall sensor + engine hood ATA switch (A38/1) (with code U60 (Active engine hood (pedestrian protection)) up to 31.05.2015)

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

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

 Trunk lid rotary tumbler switch (M14/7s1) in trunk lid central locking motor (M147)

 Glove compartment anti-theft alarm system switch (S62/7)

 Center console stowage compartment anti-theft alarm system switch (S62/32)

 Left engine hood contact switch (S62/43) (as of 01.06.2015)

 Left engine hood contact switch (without code U60 (Active engine hood (pedestrian protection)) up to 31.05.2015)

The rotary tumbler door lock switches are read by the corresponding door control unit and relayed to the rear SAM control via the interior CAN. All other switches are read in directly by the rear SAM control unit.

Function sequence for activating tow-away protection (with CODE 882 (Interior monitoring))

The tow-away protection is activated (if not previously deselected for the next locking operation) t = 10 s after the locking command from the electronic ignition switch control unit and after closing the last door and trunk lid.

The inclination sensor in the interior protection sensor determines a reference position, with which the relative vehicle inclination is compared during activation.

Determination of the reference position takes approx. t = 10 to 15 s. For this purpose an alarm can be actuated approx. t = 30 s after arming at the earliest.

The inclination sensor communicates with the rear SAM control unit with rear SAM-LIN.

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.

If the vehicle inclination sensor is faulty, all other components of the ATA continue to function properly and the corresponding fault codes are entered in the fault memory in the rear SAM control unit.

Function sequence for activating interior protection (with CODE 882 (Interior monitoring))

The interior protection is activated (if not previously deselected for the next closing) t = 10 s after the last door or the trunk is closed.

The interior protection is ready for an alarm after another t = 20 s, because it is first necessary to calibrate the interior protection sensor to the vehicle interior.

The status of the interior protection sensor is monitored by the rear SAM control unit. If a defect is detected, the remaining ATA [EDW] functions are still ensured regardless of this error. The corresponding fault codes are stored in the fault memory in the rear SAM control unit.

The interior protection can only be activated, when the armrest between the seats is closed. If the armrest is open and the driver door is opened, a gong sounds and the message "Close center stowage compartment" appears in the instrument cluster (A1). The request for this message is transmitted by the rear SAM control unit to the instrument cluster via the interior CAN.

Function sequence for activating alarm siren (without CODE 494 (USA version))

The alarm siren is armed together with the ATA [EDW] and checked cyclically approx. every t = 700 ms by the rear SAM control unit with rear SAM-LIN.

 Deactivating ATA:

The ATA is completely deactivated when the CL is opened with the transmitter key via infrared (as of 01.06.2015 not with code 889 (KEYLESS-GO)), via radio or by switching on circuit 15C (valid transmitter key inserted into electronic ignition lock control unit). The electronic ignition switch control unit transmits the corresponding signal with interior CAN to the rear control unit, which then activates the ATA.