How is Hymer Alarm wired for on / off?

[Wizardsend]

Hello, I have been trying to find out how to set / unset the Engelmann Autoalarmanlage Ultrasonic vehicle alarm system.
Vehicle is a 1990 Hymer camp 52 LHD

what I thought was a remote alarm setting switch, does not appear to do anything, so I am looking for maybe an installation manual / wiring diagram or anyone who could answer some questions.
Help would certainly be appreciated, driving me crazy.
Thank you for any advice.

 

[Chris356]

It will probably be armed by a switch inside the van with a delay on entering the van through the hab door to allow yo7 to switch it off