Can someone identify this plug?

[NikFu S.]

Just had my old aftermarket remote system replaced and I'm cleaning up the havoc the installer left in his wake.

There is a plug dangling under my dash and I'm not sure where to plug it in. My best guess it goes from the factory anti-theft system to the horns just going by the shape of the plug and the fact the alarm was triggered but made no noise.

Also my front left turn signal isn't working despite the bulb being good. I don't think there is a fuse just for that signal so I am lost. I spent a lot of time today and last night organizing wiring but didn't get anywhere on these two issues.