2004 avensis d4d t25 alarm randomly goes off

[avensisd4d786]

Hi guys my alarm goes off randomly on a night no windows are open or no attempted break in. Anyone had this problem 

[Konrad C]

A couple of things. Battery is dropping current, but more likely insects! The motion sensor may pick them up.

I have had both my older car and even the newer car do the same thing. A good clean of the interior should help.  

[Artiom]

Had exactly same problem on my Avensis T25 until I found a huge moth which was flying at night in the car :)

The same can happen if you lock the car with windows opened - the alarm will trigger from any movement nearby.

[avensisd4d786]

Thank you guys i have not come across any insects or bugs. Battery is not that old its under warranty (bosch).

[Konrad C]

Check all the door switches. I would turn off everything like the radio, heater fan etc before turning off the engine. As a test, turn off the interior light, boot/hatch light and switch the auto lights (if equipped). Switch of the elcetric seat you installed too! If the alarm triggers after all this then you a bit of a problem.

When I mentioned insects, there has been an outbreak of tiny spiders, down here at least in the South East. Every car seem to be covered in them. There are fine cobwebs in the engine bay and air intakes, plus other areas of the car. Also the temperature has risen fast (27c degrees). Not sure what the situation is like up North.

  

[Heidfirst]

you can try turning off the interior ultrasonic detector just in case it is an insect etc. flying about in the car when parked.

[avensisd4d786]

strange car hasn't happened again

[Konrad C]

That's what happened to both my cars too "I". 

The scenario are similar. I parked up some where (not on my home drive). Then anything between a few seconds up to a few minutes after locking the car, the alarm sounds. 

After resetting the alarm, it does not happen again. 

It usual happens in warm weather. I wonder if it is the car or parts expanding or contracting?

The alarm will do it only one day then, no more problems for a long time.