'Tweet' Sound When Car is Off

#1

My 2006 Monte Carlo has been making a strange ‘tweet’ sound. I only notice it when the car is off. It’s just a single ‘tweet’, a minute or so will pass, then it does it again. What could this be? I’m worried it’s something expensive.

#2

Have you owned this car since it was new, or did you purchase it as a used car?

#3

Does the tweet sound like it’s inside the cabin, or outside?

Does the vehicle have an after-market alarm system?

#4

“Does the vehicle have an after-market alarm system?”

One of the reasons why I asked if this car was purchased as a used car is because all manner of aftermarket modifications could have been done to the car prior to the OP buying it.
That is just one of the…joys…of buying a used car.

#5

My wife had this same complaint about her 2003 Chevy Blazer. I went out to check it and the “little red light” next to her radio was keeping perfect time with the annoying little tweet. I found the source of the tweet and crushed it with a pair of pliers. I later disconnected the wires to the tiny speaker just to make sure the “tweet” was dead.