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Looking for constant 12 volt and ignition wire

Discussion in 'Gen 3 Prius Accessories and Modifications' started by tekstyle, Jun 7, 2015.

  1. tekstyle

    tekstyle Junior Member

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    Hi there, i am looking for a suitable constant 12+ volt wire and a 12+ wire thats only on when ignition is on and off when ignition is off. Both needs to be somwhere on the front passenger side and can handle about 4 amp of power draw.

    The only other place i can think of is from the radio harness but i want a more accessible location. I also have no idea where the ignition wire is on this thing considering it doesnt have a starter and no key tumbler.

    Thank you.
     
  2. ChapmanF

    ChapmanF Senior Member

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    If what you're really wanting to find is existing circuits to tap into that are located where you want them and switched the way you want, and how much they are fused for, and what else is already on them so you can judge how much is left for you, your Wiring Diagram Manual on techinfo.toyota.com is where you'll find all that stuff. Section G will show you exactly where all of the wire harnesses are routed through the body, section H shows you all the individual circuits, the wire color codes, and the connector codes and pin numbers. The connector codes you can look up in section K which has pictures of all the connectors showing their shapes and colors (section G again is where you see their locations in the car.)

    At least, that's the way my 2001 is organized - I don't know if they've kept the same section numbering in 2012 but I'm sure you'll be able to find the same stuff either way.

    Another option that's always easy in a Prius is to run your new circuit straight from a fused tap off the 12 volt battery, which is conveniently inside the car. The positive battery terminal clamp (again, if they haven't radically changed the design) contains a high-interrupt-rating fuse, so the best place for you to tap from is the screw terminal on the non-battery side of that fuse ... then you add your own normal-rating fuse sized appropriately for the load you're adding, and the OEM fuse ensures your fuse won't have its interrupt rating exceeded.

    That circuit would be on all the time. To get one that switches on and off with the car, it's easy to exploit the very handy fact that whenever the car is ON, well-regulated voltage at about 13.8 is coming from the DC/DC converter, and when the car is OFF the voltage will always be 12.8 or lower from the battery. The first time I did this I just threw together my own voltage-based relay control out of mostly junk-drawer parts, but later I found there's a nice product you can buy for doing exactly that (with several nicer features than my junk-drawer version).

    -Chap
     
  3. tekstyle

    tekstyle Junior Member

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    • This thing is very useful. Thanks for sharing this. I might find applications where i can put this to good use. Currently, i am using a power magic pro that is used for dashcams (blackvue). very similar, except, it wont not turn back on after it gets shut down unless power is applied to the ignition sense wire. I will look into the one u provided as it seems more suitable for a non hybrid. In the prius, if the battery drops below a certain voltage, the HV battery will recharge the aux battery. The problem with this is that for really extended peroids of time when the car is not on, the HV battery might be drained as well as it tops off the aux battery. This might pose a problem to turn over the ICE in the case the HV battery isnt sufficiently charged enough to turn the electric motor.
     
    #3 tekstyle, Jun 7, 2015
    Last edited: Jun 7, 2015
  4. kenmce

    kenmce High Voltage Member

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    windshield wipers?
     
  5. nedear88

    nedear88 My 1st Prius.

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    12V round plug under the bridge, this should be 10 AMP.
     
  6. tekstyle

    tekstyle Junior Member

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    What bridge are you referring to?
     
  7. Eugene Hong

    Eugene Hong Member

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  8. ChapmanF

    ChapmanF Senior Member

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    Sorry, I caught this on the other thread earlier but not here.

    Just so future readers won't get the wrong idea, the Prius only uses power from the HV system to charge the aux battery when the car is in READY mode. (In that mode, it also starts the engine whenever it needs to, to keep everything properly charged.)

    When the car is not on, the system main relays isolate the HV battery completely, and the aux battery is on its own.

    This is why using a voltage-triggered switch like the VCM-06 on a Prius works really well, and does just what you would want it to. In fact, it works especially well on a Prius, because the DC/DC converter has a very stable regulated output (right around 13.8 volts all the time while the car is READY, regardless of driving conditions etc.). That gives a reliable difference of a whole solid volt between what the switch sees whenever the car is off, and what it sees when the car is READY. Conventional cars with alternators could have voltage swinging around between 12-something and 14-something and you could sometimes see the headlights go dim at idle and bright when goosing the engine. That made picking a switch trigger voltage kind of an art. No such trouble on a Prius.

    -Chap
     
  9. Figster10

    Figster10 Member

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    Where did you find the ignition wire to be? I’m having trouble locating it to install a gps starter disabler
     
  10. Montgomery

    Montgomery Senior Member

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    Hi Tekstyle, I'm not good in this area with newer cars, but if you go into the section that talks about installing aftermarket Head Units, they go into detail regarding finding various power sources. I remember seeing someone do what you are asking, but I read it years ago in the Head Unit section and can't remember who/what it was about. But, its in there.
     
  11. Figster10

    Figster10 Member

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    Thanks for the reply,
    I spoke with a car alarm tech guy and he said Prius especially gen 2 is a bit different for starter/disabler hence why I just went with locator only with this hook up which was much easier. I would need to rig it up a little more than your normal engine cutoff turn key hook up and of course if I decided to sell the car it would be more of a headache to securely remove the unit and put back to normal.

    So, it is possible to hook up but some extra stuff is required and it is a little more stressful to remove once you sell the car or whatever.
     
  12. RacingSystems

    RacingSystems Junior Member

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  13. Figster10

    Figster10 Member

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    Okay, that’s where I’m at right now because I have a continuous 12v wire bottom left side of driver side. There I’m able to have power neg and positive to keep gps tracking device powered but now with the push start key feature I am trying to see where I can split a wire to be able to disable the car if stolen or I want it returned. The tech to the company suggested rigging some weird way that could be difficult to backtrack should I decide to sell car later. Please help me and thank you...

    I have experience hooking up the turn key cars with this device but of course this gen2 2007 Prius can be tricky