Originally Posted by
GraphiteGhost
As far as I know, no one set up a horn beeping when the car is locked or unlocked. The beep that the siren does is a 'chirp' that is built in to the newer sirens. You can put a 'chirping speaker' in the under hood fuse box, wired to a relay already there. Searching chirping in the forum, that might find the posts. Good luck!
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Super easy, grab a small "sonalert" or sounder of some sort that works on 12 volt DC. You connect it from the coil's hot side to ground on the Remote Keyless Entry relay in the driver's side underhood fuse box.