Alarm issue

[Swirl3d]

The alarm on my 2008 Toyota Prius often goes off at random and its driving me to despair.

I have been trying to fix this issue for years and have spent over a grand in labour at various garages trying to resolve it, to no avail. The dealer is the most unhelpful, and basically won't do any fault finding as it doesn't have plug in diagnostics. 

I used to think it was over sensitivity as it would go off if passed by a speeding car, but now am convinced there is a fault somewhere as it will go off in the dead of night with no traffic (which it has done twice tonight, hence my writing this at 5am).

For the sake of my sanity and neighbours, if I don't sort the alarm issue I will have to scrap the vehicle and I won't be replacing it.

Info 

- parked on street, sometimes several streets away so it may go off mire frequently but I don't hear it.

- new 12v Battery last year

- internal sensor removed, alarm still going off but slightly less frequently 

- nothing in sunglasses compartment 

- also have an issue with the rear heated windscreen not working and blowing a big fuse

- one mechanic once mentioned something about a leak on the rear door poss causing the windscreen issue 

- car is driven infrequently (once a fortnight or so) but generally long distances (200 miles plus) when driven 

- alarm has gone off when vehicle has been sat a while, but also when driven earlier that day or week. 

Any help appreciated. I am not very car savvy so will need to be talked through any work/checks

[Bper]

There are a number of posts regarding this problem with the alarm going off at random times causes from nearby phone masts , sunglasses, faulty sensors, bad earth connection, mobile phones, low Battery in key fob, etc.

Some have mentioned disconnecting the alarm completely and this is the method given by a member in one of the posts below should you consider trying this.

If a Toyota service cannot find the problem I would contact a good car alarm installer and discuss the likely causes of this.

 

Method posted on forum.

you have to reset alarm ... it's very simple . or turn off alarm .  under the bonnet on the right hand side there is a fuse box .  in the fuse box   . 

u see the brown fuse on the top go down . number 6 its a blue fuse  . OR [ the 2 blue fuse next to each other  .  u want the top one ] 

THIS fuse controls 5 things . ..  alarm .  central locking system   .  power steering   .  radio and clock in the car . . 

when you remove the number 6 blue fuse you can still drive your car just remember you will not have this 5 things .  . OK NOW HOW TO RESET ALARM .

in the fuse box you will see a white pick u need that to remove and put back the fuse .  unlock your car and remove the blue fuse  

then leave your door open and put key fob in the ignition and put the fuse back . and that it the alarm should be reset . 

PS try replacing it with a new fuse .