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Alarm problems

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by IanX, Aug 12, 2017.

  1. IanX

    IanX New Member

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    Joined:
    Aug 12, 2017
    Your Mercedes:
    SL500 1998 Engine 119.982
    Hi, on my 1998 SL500 I'm having problems with the alarm. Last Sunday I unlocked with the remote, opened door, climbed in, but when I started the engine the alarm went off. Yesterday after setting the alarm with all doors/windows/bonnet/boot/hood closed the siren started beeping (less than one second) several times, then settled down and was silent. Another time I unlocked with the remote and the alarm went off.
    I believe the alarm is the factory fitted alarm. The manual says 3 flashes from indicators when arming and one when disarming and that the alarm can be deactivated by turning the ignition on. All these work as advertised. One thing that does not work is the closing of the windows when I long press the lock button on the alarm. Also another odd thing is that the siren unit under the bonnet has a scorpion logo on it (you have to take the siren out to see it).
    At the base of the drivers door A pilar there is a LED which flashes every 3 seconds when the alarm is set, and a little 3 pin connector. Does anybody else have this? (see pictures)
    I'd like to know where the Alarm / Security System module is in the car. Does anybody know? Any other help would be kindly received. Thanks!

    Alarm Documentation.JPG Alarm Scorpion Siren.JPG Alarm LED and Plug closeup.JPG Alarm LED and Plug.JPG
     
  2. OP
    IanX

    IanX New Member

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    Joined:
    Aug 12, 2017
    Your Mercedes:
    SL500 1998 Engine 119.982
  3. Paul1948

    Paul1948 Senior Member

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    Location:
    Bournemouth
    Your Mercedes:
    S320 CDI 2003
    Scorpion alarm is an after market alarm, the mercedes alarm is normally under the the drivers side wing behind the cowling..expect this is actually dead...very common fault.
     
  4. OP
    IanX

    IanX New Member

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    Your Mercedes:
    SL500 1998 Engine 119.982
    Thanks Paul, Is that RHS front or rear wing for the Mercedes alarm unit? Any photos available? I was vaguely hoping that Mercedes fitted Scorpion sirens to their cars, but I guess you think this unlikely. Also looking at the wiring to the siren it is insulated with plastic tape, rather than the fabric tape used by Mercedes, so again suggests aftermarket.
    I guess the Scorpion alarm must be fitted close to the original Mercedes alarm so it can pick up on all the inputs.
    Out of interest what is the light blue pipe that is heading towards the offside (RHS) headlight area?

    Alarm wiring.jpg
     

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