No audible chirp when I lock the doors on my '05 T with either of the 2 FOBs. I bought this vehicle used and I love it but this little issue has me mystified. It used to chirp when locking doors and then it stopped after a stop at a full service car wash where the attendents had to drive it to the automatic car wash machine. It stopped working or chirping after that. Then it seems I got it working again by pressing the alarm button on the FOB while the key was in the ignition. But apparently that was a coincidence because it seemed to stop chirping on it's own and I can't make it work anymore. I'm afraid it has something to do with the Anti-theft system and maybe the anti-thft system isn't arming anylonger when I lock the doors?