Sticky Thread on Gen 2 Prius Alarm Fix?

Writing this thread at 2AM due to having the Prius wake me and neighbors up. I have a 2005 Toyota Prius which the alarm tends to go off quite frequently at 2am-3am in the morning has been happening around once a week. This seems to be incredibly common issue when using the search function yet I see know definitive answer on what causes the issue. My goal is to determine what that issue is and have a sticky thread so anyone in my shoes doesn’t make enemies with their neighbors.

Facts:
-New 12V Battery
-I have Techstream software and option to disable horn from alarm seems to be non existent possible pointing to the dealer installed alarm I’ve read about?
-If is Toyota dealer alarm, I cannot find the sensitivity adjustment under the dash that I have seen in Tacoma threads
-Car kept outside, which their may potentially be cats however no other vehicle in driveway has ever done this and neighbors cars also do not do this.
-If I could disable the alarm, I and several other unanswered threads starters would be interested in doing so, however I don’t see any consistent or source on doing so, one says Techstream well I have a Techstream and it’s not an option in the settings. The other says take apart hood cowl and disconnect switch, does that mean I would be riding around with a hood ajar light?

 

Also has anyone actually fixed the problem themselves and if so what was the underlying cause of the issue? It seems the majority of these alarm going off threads have speculation but no definitive answer?

 

12v battery is good oem Toyota battery, I installed it and has a good solid ground can rule that one out. Nothing in the sun glass holder, will replace battery in the fob ASAP and report back.

For gen 2, I would say it’s common enough to where I even read the dealers had a sticker on a loaner saying don’t put anything in the sunglass holder. There’s even YouTube videos for Tacoma on how to adjust the sensitivity for the same alarm, however for the Prius I cannot find the adjustment control. For this particular generation with this particular alarm, there is more reported false alarm issues than any car I’ve seen.

 

I want to say when we got this car a year ago the first thing I did was replace the key fob cover with new one from eBay, something I usually do when buying a used car with worn out fob. I’ll go ahead and order another key Fob cover & buttons if the price is right, to test and inspect the fitment of the buttons.

 

Using the Techstream tool I disabled the panic feature from the key fob, then under options enabled security which interestingly wasn’t enabled, not sure why that was the case.

After that I could access the security menu and turn off the horn for the alarm. Will see if this works, as not sure if it’s the dealer installed alarm I’ve read about or factory alarm and which one of those is and isn’t controlled through ecu.

 

Alarm has yet to go off again, however if it does I will make sure to post back here. So to me seems that you actually can tweak the alarm settings on the Techstream app interestingly enough by enabling security in options(if not already, wasn’t enabled for me) which then allows you to customize the security parameters. Then from the security parameter should have an option for disabling horn on alarm on a gen 2 Prius. Then for safe measure I also disabled the panic feature in the remote menu.

 

Well after waking both my wife and I, and neighbors up on several occasions the objective was to stop doing that, so I wouldn’t call this throwing in the towel (as long as what I did fixed it).

However if I were to drop it off at the dealer and let them diagnose and come up with a costly bill, I would have called that throwing in the towel IMO.

 

As far as I have learned it can have a tendency to interfere with the windshield security sensor for some reason. Saw somewhere that the Toyota dealers where aware of the issue as well.

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Yes I think it is called a Glass Break Sensor, however in the attached PDF the only thing I see if a microphone located under lower dash panel so nothing to do specifically with the windshield. Also in the Prius Alarm Install file I found in a 2006 thread interestingly enough I found the location of the dial to adjust the sensitivity which looks to be located under the "lower dash cover".

 

Yes three that I could find quickly.

 

It’s on the Toyota Tacoma forums too, and I also saw there is a YouTube video showing how to fix the problem on a Toyota Tacoma which involves adjusting the sensitivity. In the Toyota install instructions I see they have step which calls to set the dial to 9, maybe that level of sensitivity was a bad idea for all equipped Vehicles without proper testing.

https://youtube.com/watch?v=JrD_p5Z--KY