I asked a long time ago about a tick-tock sound coming from the dash somewhere. Every 5 seconds it would tick-tock, like a turn signal flasher. I narrowed it down to definitely the passenger side, definitely electrical (not a vacuum door on the HVAC), always while ignition key was in RUN even when engine not running. Then the other day I had a break through- it tick-tocked when I opened the door, after turning off the car and sitting for a minute. Security? Not HVAC electrical for sure. I took off the lower foot panel and the glove box door, and listened. The BCM? Oh man.
Then I remembered I had taken out the fuse for the interior courtesy lights about a year ago (to save electricity for my tiny battery, to not have to have the rear view mirror lights go on or accidently get bumped on). Let me try that- HALLELUYAH. Tick tock noise stopped immediately. So, if that fuse burns out or you take it out, you get that annoying sound like a flasher or slowly going bad relay.