Nonstop alarm after working on power window

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by LegeetSheet, Feb 25, 2021.

Tags:
  1. LegeetSheet

    LegeetSheet New Member

    Joined:
    Feb 25, 2021
    5
    0
    0
    Location:
    Ohio
    Vehicle:
    2004 Prius
    Model:
    ----USA----
    I fixed my driver’s side window regulator on my 2004 Prius yesterday and after putting the door back together, my car alarm now goes off instantly after the key fob is removed from the ignition. That being said, the door was left ajar between 1-2 hours while I was doing the work. Any ideas?

    Note: I’ve had this problem in the past when the 12V battery was on its way out, but it has since been replaced ~6 months ago.
     
  2. TMR-JWAP

    TMR-JWAP Senior Member

    Joined:
    Aug 12, 2016
    3,917
    4,372
    0
    Location:
    Columbia, SC
    Vehicle:
    2007 Prius
    Model:
    Touring
    have you tried cycling the locks using the fob?

    any chance the fob button is stuck? Is the small red LED lit in the upper right corner of the fob when you take it out of the slot? Does your car have sks (small black button on door handles?)

    any chance the 12v battery is near dead from door being open a few hours?

    maybe the fob battery is near dead from pinging with the car the entire time the door was open?

    just throwing things on the wall..
     
    LegeetSheet and PriusCamper like this.
  3. PriusCamper

    PriusCamper Senior Member

    Joined:
    Mar 3, 2012
    5,643
    2,290
    0
    Location:
    Pacific Northwest, USA
    Vehicle:
    2007 Prius
    Model:
    Two
    Maybe disconnect 12v battery for 5 minutes and see if that method of resetting the computers fixes it?
     
    LegeetSheet likes this.
  4. pasadena_commut

    Joined:
    May 2, 2019
    286
    92
    0
    Location:
    Southern California
    Vehicle:
    2007 Prius
    Model:
    N/A
    If the door sensor wire was pinched so that it is now shorted to ground, or the sensor switch was stuck in the "door open" position (electrically shorted) somehow, what you are observing would occur. If you close all the doors does the dome light stay on (as it would if a door is open)? If you turn on the car is the door open dashboard light lit?

    The thing is, that sensor is mounted on the jam and you were working on the door itself. When the door opens that switch plunger pops out and shorts the sense line (otherwise pulled up to 12V) to ground. If a bit of conducting material broke off inside the sensor the car might think the door was always open. That would set off the alarm, I think. The sensor/switch is easy to remove if you have the right drive bit, but on my car only 1 of 3 doors had enough slack to pull it forward to unhook it. For the others the inside trim would have also needed to be removed to service it.

    Just for yucks you might try opening the door and pressing the plunger a bunch of times to see if that clears the problem, at least temporarily.
     
    LegeetSheet and PriusCamper like this.
  5. LegeetSheet

    LegeetSheet New Member

    Joined:
    Feb 25, 2021
    5
    0
    0
    Location:
    Ohio
    Vehicle:
    2004 Prius
    Model:
    ----USA----
    The fob button could be stuck, but I would’ve had that problem before I did the work. The car does have sks, though I’m not sure what that would do.

    The 12V battery was definitely drained a bit. I charged it with a trickle charger for awhile and checked the voltage with the info button headlights 3x procedure and it was at 11.8V.
     
  6. LegeetSheet

    LegeetSheet New Member

    Joined:
    Feb 25, 2021
    5
    0
    0
    Location:
    Ohio
    Vehicle:
    2004 Prius
    Model:
    ----USA----
    The door sensors appear to be working properly. The light illuminates when a door is opened and isn’t when they’re all closed. No dome light shenanigans either. Where would the sensor wire be in relation to the door? I’d imagine I’m going to have to open it all back up again eventually.
     
  7. pasadena_commut

    Joined:
    May 2, 2019
    286
    92
    0
    Location:
    Southern California
    Vehicle:
    2007 Prius
    Model:
    N/A
    That doesn't sound like it is the door sensor, if it was the dome light would stay on and the door open indicator would be lit. If you open the door and look at the jam on the car there is a little black plastic piece with a plunger button on it. The wire runs down the pillar from the back of that, then along the raised section under the door towards the front of the car.

    I just noticed that you said the alarm goes off as soon as the fob is removed. That is strange because the alarm is supposed to have an arming interval, something like 60 seconds, before it can respond to any alarm events. (Assuming factory alarm, if you have an aftermarket alarm on it, who knows?) So now I'm leaning towards a screwed up fob with the alarm button pressed down or shorted. If you still have two of them, put the one you have been using in a metal box (or wrap it in foil a couple of times) and leave it in your house, then try the other. If that works then take out the busted one and disassemble and clean it.
     
    LegeetSheet and PriusCamper like this.
  8. LegeetSheet

    LegeetSheet New Member

    Joined:
    Feb 25, 2021
    5
    0
    0
    Location:
    Ohio
    Vehicle:
    2004 Prius
    Model:
    ----USA----
    It definitely might be a fob issue. Both of the fobs I have are pretty worn, I’ve been meaning to get new cases for them. Would turning off the smartkey function (the black smart button under the steering wheel) take a faulty fob out of the equation?
     
  9. pasadena_commut

    Joined:
    May 2, 2019
    286
    92
    0
    Location:
    Southern California
    Vehicle:
    2007 Prius
    Model:
    N/A
    Smartkey should not matter, if it is the fob it is probably the panic button stuck down, or worse, the switch it activates shorted.

    There are a few threads already on this problem, and in this one:

    Prius alarm will NOT stop! | PriusChat

    one person said it had been the fob in their case.

    Are the hood and hatch fully closed? There are sensors for those too and maybe if the hood is open the alarm goes off right away?

    My money is on a messed up fob though.
     
  10. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    11,975
    8,676
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    The door lock actuator, inside the door where you were working, has a sensor of its own to detect movement of the locking mechanism and whether it is happening because of the mechanical key from outside. (In a working Prius, with the car off and armed, try moving the inside lock twisty to unlocked and see what happens.)

    If the wiring to that got disturbed during the window work ....
     
Loading...