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Emergency Alarm Function - GF82.25-P-2011LF

Model 222 with code 934 (Taxi emergency alarm unit) with code 965 (Taxi/rental car - electrical pre-installation) 

Emergency alarm, general 

The emergency alarm function is a protective device for the taxi driver. The emergency alarm can be triggered by the taxi driver if he/she feels threatened by someone. At the same time, a radio help call can also be triggered.

The emergency alarm function consists of the following subfunctions:

Function sequence for emergency alarm 

The emergency alarm can be activated using the emergency alarm system radio remote triggering transmitter (A8/4) or using the emergency alarm system "Trigger" button (S62/6) concealed in the driver footwell.

An active emergency alarm is ended by pressing the emergency alarm system "Clear" button (S62/5). The special-purpose vehicle multifunction control unit (N26/9) reads in the status of the emergency alarm system "Clear" button directly and terminates the alarm output.

IMPORTANT Depending on the programming, a radio help call can also be triggered.

The following variants of the emergency alarm can be output:

Silent alarm 

The silent alarm is intended to prevent the threatening person from noticing the alarm.

The silent alarm is requested by pressing the emergency alarm system "Trigger" button. The multifunction control unit reads in the status of the emergency alarm system "Trigger" button directly, evaluates it and then starts a radio emergency call.

IMPORTANT Detailed information on the radio emergency call is available in the "Function sequence for radio emergency call" chapter.

Full alarm 

In the event of a full alarm, the following functions are also triggered in addition to the output of the silent alarm:

The full alarm is requested by actuating the emergency alarm system "Trigger" button or the emergency alarm system radio remote triggering transmitter twice within t = 3 s. The multifunction control unit reads in the status of the emergency alarm system "Trigger" button directly.

When the emergency alarm system radio remote triggering transmitter is activated, it sends a radio signal over the FM 1, AM, CL [ZV] and KEYLESS-GO antenna amplifier (A2/18), electronic ignition lock control unit (N73) and the interior CAN (CAN B) to the multifunction control unit.

IMPORTANT For safety reasons the full alarm, triggered by the emergency alarm system radio remote triggering transmitter, is automatically repeated after t = 30 s.

A reset takes place by pressing the emergency alarm system "Clear" button. The multifunction control unit reads in the status of the emergency alarm system "Clear" button directly.

The radio emergency call is also reset in the vehicle using the emergency alarm system "Clear" button, but depending on the radio system it can be necessary to deactivate the radio emergency call in the radio system.

The multifunction control unit evaluates the incoming request to issue the full alarm and sends the "Switch on exterior lights", "Switch on interior lights" and "Switch on horn" requests over the interior CAN to the front SAM control unit (N10/6).

Exterior lights:

The following functions are actuated and they flash on and off:

IMPORTANT Detailed information on the actuation of individual components of the exterior lights can be found in the separate function description "Exterior lights, function".

Interior illumination:

The interior illumination is switched on.

IMPORTANT Detailed information on the actuation of individual components of the interior illumination can be found in the separate function description "Interior illumination (IBL), function".

Acoustic alarm:

The front SAM control unit actuates the left horn (H2) and the right horn (H2/1) through the horn relay (K40/8kL) in the engine fuse and relay module (K40/8) at a frequency of f = 1.6 Hz.

Function sequence for radio help call 

Depending on the programming, a radio help call can be made separate from or together with the emergency alarm.

The radio help call is started by:

The multifunction control unit reads in the status of the emergency alarm system "Trigger" button directly and evaluates it.

The radio signal from the emergency alarm system radio remote triggering transmitter is received by the multifunction control unit over the FM 1, AM, CL [ZV] and KEYLESS-GO antenna amplifier, the electronic ignition lock control unit and the interior CAN.

The multifunction control unit then sends an emergency alarm signal over a direct line to the two-way radio (A49) (accessories) or the radio data transceiver (A49/5) (accessories).

The two-way radio or the radio data transceiver then sends a radio emergency call over the radio roof antenna (A28/9) to the taxi control room.

Depending on the programming involved, the radio emergency call can be issued as a "static" or as a "pulse" signal.

With "static" actuation, the discrete output on the multifunction control unit is switched to the ground connection when a radio emergency call is made until the radio emergency call is reset using the emergency alarm system "Clear" button. The multifunction control unit reads in the status of the emergency alarm system "Clear" button directly.

With "pulse" actuation, the discrete output on the multifunction control unit is switched to the ground connection twice for t = 1_s when the radio emergency call is made, with a break of t = 1_s between the pulses.

An active radio help call is ended by pressing the emergency alarm system "Delete" button. Often, however, it is necessary to restart the two-way radio in order to reset the radio help call in the two-way radio.

Function sequence for display of fault messages 

Fault messages are displayed in the instrument cluster (A1). The multifunction control unit recognizes and stores any faults and malfunctions that occur.

If one of the following faults is pending, the multifunction control unit sends a request to issue a text message over the interior CAN, electronic ignition lock control unit and the user interface CAN (CAN HMI) to the instrument cluster:

The multifunction control unit also sends data logs cyclically over the interior CAN, electronic ignition lock control unit and user interface CAN to the instrument cluster.

IMPORTANT During diagnosis using the diagnostics tester a message is also shown on the instrument cluster.

  Electrical function schematic for emergency alarm   PE82.25-P-2060-97SEA
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