1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Key switch power in headliner?

Discussion in 'Prius v Accessories and Modifications' started by MattFL, Oct 15, 2024.

  1. MattFL

    MattFL Member

    Joined:
    Dec 3, 2007
    171
    49
    0
    Location:
    Florida
    Vehicle:
    2008 Prius
    For a 2012 Prius, is there any power in the headliner/map-light area that switches on/off when the car is switched on/off? I'm installing a dash cam and it would be super convenient if I could get power from up there.
     
    #1 MattFL, Oct 15, 2024
  2. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    8,486
    5,050
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    No. Unless you have a factory homelink mirror.
     
    #2 rjparker, Oct 15, 2024
    Air_Boss likes this.
  3. Air_Boss

    Air_Boss Senior Member

    Joined:
    Jun 2, 2012
    4,035
    1,110
    0
    Location:
    New Yawk
    Vehicle:
    2012 Prius v wagon
    Model:
    Five
    I used the switched, proximate Homelink circuit to power the radar detector.
     
    #3 Air_Boss, Oct 15, 2024
  4. MattFL

    MattFL Member

    Joined:
    Dec 3, 2007
    171
    49
    0
    Location:
    Florida
    Vehicle:
    2008 Prius
    Thanks for the info. I'm not sure which mirror is in there (my wife's car), what identifying marks should I look for to identify it as homelink or not? Also would the car not be wired for a homelink mirror even if it didn't have one? My thought is it's a snap-in option, but maybe I'm wrong?
     
    #4 MattFL, Oct 15, 2024
  5. Air_Boss

    Air_Boss Senior Member

    Joined:
    Jun 2, 2012
    4,035
    1,110
    0
    Location:
    New Yawk
    Vehicle:
    2012 Prius v wagon
    Model:
    Five
    The harness isn't present on a v without a factory Homelink mirror, but can be added.
     

    Attached Files:

    #5 Air_Boss, Oct 15, 2024
  6. rjparker

    rjparker Tu Humilde Sirviente

    Joined:
    Jun 6, 2008
    8,486
    5,050
    7
    Location:
    Texas Hill Country
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    Dealers have a battery powered homelink mirror they can add which requires no wires.

    The easiest thing to do for a dashcam is to run a power wire down to the fuses and install a fuse tap. You can get unswitched 12v and ground at the map lights or pickup everything at the interior fuse box.

    Some dashcams can be wired to unswitched 12v and use logic to go into a sleep mode based on a loss of the higher charge voltage when running. Others will wake up if their impact or motion sensor detects something.
    IMG_6434.jpeg

    This is what your map light will have:

    20 pin schematic.jpeg
    As a side note, if you manually turn on a map light it will not turn itself off when you leave the car. A guaranteed dead battery in the morning.
     
    #6 rjparker, Oct 15, 2024
    Last edited: Oct 15, 2024
    Air_Boss and MattFL like this.
  7. MattFL

    MattFL Member

    Joined:
    Dec 3, 2007
    171
    49
    0
    Location:
    Florida
    Vehicle:
    2008 Prius
    Thank you very much, this is extremely helpful info about the plug! I was thinking of using the voltage as a trigger, so the camera can act as a security camera for a short time after the car is turned off (as the battery voltage naturally comes down). In my truck I have one of those things that is supposed to run the camera until the battery voltage hits 12.x volts, then turns off the camera so as not to kill the battery... but it's a bad design and the device itself kills the battery after about a week of sitting (I work from home so it sits a lot). So I might make one myself that's more efficient. I can tell by the headlight brightness on the Prius that the 12v voltage comes up significantly as soon as the car boots up, so it should be a pretty easy trigger.
     
    #7 MattFL, Oct 18, 2024
    Air_Boss likes this.
  8. Air_Boss

    Air_Boss Senior Member

    Joined:
    Jun 2, 2012
    4,035
    1,110
    0
    Location:
    New Yawk
    Vehicle:
    2012 Prius v wagon
    Model:
    Five
    I use a12.7V relay to trigger the fogs for use as DRLs. Works fine. Has about a 30 second dwell after ignition cutoff.
     
    #8 Air_Boss, Oct 18, 2024
    MattFL likes this.
  9. ChapmanF

    ChapmanF Senior Member

    Joined:
    Mar 30, 2008
    24,902
    16,209
    0
    Location:
    Indiana, USA
    Vehicle:
    2010 Prius
    Model:
    IV
    I've used a similar voltage-controlled switch and been happy with it. Turns on when the car is made READY, and can be set to stay on for a certain amount of time once the car is not READY (but will always turn off anyway if the battery voltage gets below a lower setting).
     
    #9 ChapmanF, Oct 18, 2024
    MattFL and Air_Boss like this.
(You must log in or sign up to post here.)