I noticed the same thing on my Dad's TC. No key in the ignition, but every time I opened the door I would hear the chime dinging. The problem was the headlight knob. You pull on the knob for the lights to go on and push it in to turn them off. But, after looking through the manual, I found out that the knob turns to the left and to the right also. I turned the knob to the left, and no chime. I hope this fixes your issue.