Prius had been put to bed for the night, with all doors properly shut, in a garage. An hour later the alarm goes off. No animals or children were left in the car and there's unlikely to be a rat, mouse or other intruder. Alarm stopped after 30 seconds, before I had time to get to the car. Any suggestions for the cause? Car is less than 2 months old. Incidentally OWNER'S MANUAL index has no entry under "Alarm". You have to look for "Theft deterrent system (p.63) and I see that this is on right-hand drive vehicles only. Don't left-hand vehicles need such a system? Or does it go by some other name?
I've been dealing with false alarms on my first Prius for years. It's one of the first bought in Oct. of 2000. I'll try to make a very long story short (but I must add that at one point they told me I did not have an alarm). The best probably cause to date, is it is getting a false Panic button signal. I am now waiting for instructions on how to disconnect the wireless transmitter. Won't be able to use the FOB to unlock the doors but we'll see if it still happens. It took a couple of years to get to this point. I know it's an older model, but it's been a chronic, and the only, problem.
I am seeing the same problem in my prius 2007 model. figured out when the alarm went on, the red light in the FOB also got triggered So somehow the FOB has send the signal for theft alarm. Removed the FOB battery and in manual mode now. Awaiting for some time to see the results, Ok for past few hours. The theory I believe is linked to the 12V battery dying out or going below certain charge, when it searches for the FOB in a nearby location before going to hibernation to avoid scanning the key around thus to save battery. It is here when it fails and either a software flaw or a hardware flaw causes the theft alarm to get triggered.
