I had the battery disconnected for a number of weeks, related to a battery rundown issue (may need a separate post on that later), and not having time to get back to the job.


Now, when I reconnect 12V at the battery, I get flashing lights and horn (I've now removed the horn fuses to avoid disturbing the neighborhood). It stops after a minute or so. Also stops with turning key in ignition. But after removing key or opening door, it starts again.


How do I get the security system back to normal operation?


FYI, I only have keys, no fob.

 

Solved! For now...
Connecting a new battery in place of the old (not just parallel) allowed re-connection without the alarming lights and horn!
Now I can get back to my no-crank issue, but I know there's plenty of help to check out first at Gentlemen (No) Start Your Engines.