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I would be very surprised if anyone on this forum responded with information on this subject as in most countries operation of such a unit is deemed a felony unless you are a bone fide locksmith, alarm installer/repairer, security consultant etc.
Note that I say operation - not ownership.
If it is a particular alarm you need to disable then contact the manufacturers and explain the problem. Some will help if you can prove ownership & some will not.
If they will not help you then go to your local car alarm installer and ask them to help.
If all this fails then SEARCH THE WEB.
You will have to pay for the plans and someone will have a record of your name and address.