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constant power source fuse box

Discussion in 'Prius c Accessories and Modifications' started by rock88, Aug 25, 2013.

  1. rock88

    rock88 New Member

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    HI there,

    I am looking for a constant power fuse to tap into.I was told to say away from oringal fuses for the Ecu, sensors and digital displays.
    Does anyone know which fuse i that has constant power and need a fuse for acc as well.
    Any suggestions would great
    Heres a diagram of the cabin fuse box
    Thanks View attachment 56705
     

    Attached Files:

    #1 rock88, Aug 25, 2013
  2. steveoknievo

    steveoknievo Member

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    What are you trying to do with this? You could hook straight to the 12v battery if you weren't worried about a dead battery depending on what you're trying to power..
     
    #2 steveoknievo, Aug 27, 2013
  3. rock88

    rock88 New Member

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    Ya I only have one fuse that is only hot when I turn the car in and off when the car is off . Now I have already connected that to the monitor for my rear camera . Now I need another fuse that only is only hot when he car is on . I need this for a dummy alarm which has the red positive in a constant fuse which I will use the front fogs and need the negative black to a fuse that is only hot when the car is on . Now some suggested that since the led dummy alarm uses like less than 3 amps i could connect the negative black from the dummy alarm to my positive red in my cigerette socket which only comes in when the car is on any suggestions would be great
     
    #3 rock88, Aug 27, 2013
  4. rock88

    rock88 New Member

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    The is if U hook up a device to the battery wouldn't that stay on all the time
     
    #4 rock88, Aug 27, 2013
  5. tk1971

    tk1971 Active Member

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    I had a "fake" alarm once upon a time in a 81 Datsun 210 SL. Used a blinking red LED from Radio Shack. Connected the + of the LED to a constant battery 12V+ connection. I used a multimeter to find an ignition source in the fuse box that happens to be grounded when the ignition is not on. When the ignition switch is on, both + and - of the LED gets +12V, so the LED is off. Get a multimeter and start probing with the car on and off. The LED draws negligible current when on. In the 210, the LED outlived the car.
     
    #5 tk1971, Aug 27, 2013
  6. rock88

    rock88 New Member

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    thanks for the replay , so i can connect the negative black wire on the led with my back up camera monitor positive red wire to the acc fuse , so just connect them in to the fuse tap wires and stick a 10 amp fuse in the extra slot on the fuse tap thanks
    since this is a hybrid , she not be any different than a regular gas car. thanks
     
    #6 rock88, Aug 27, 2013
  7. tk1971

    tk1971 Active Member

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    By connecting the LED negative to the positive camera monitor feed wire, you may end up powering up your camera monitor (since the negative lead is grounded). You need to find a fuse location that is +12V when the car is on and ground when it is off.
     
    #7 tk1971, Aug 27, 2013
  8. rock88

    rock88 New Member

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    yes i found a fuse (coming from my front fogs ) i used a current tester and that was hot when the car was off and on.
    so i connecting the fake alarm postive to that and the black to acc but there i only one acc that i could detect in the fuse box the other has to do with ecu , and i was told not to fuse tap anything device to a fuse that controls the ecu, computer , sensor or digital displays.
     
    #8 rock88, Aug 27, 2013
  9. tk1971

    tk1971 Active Member

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    I don't think the blinking LED will negatively impact anything. What about the fuse to the radio or the cigarette lighter 12v?
     
    #9 tk1971, Aug 28, 2013
  10. rock88

    rock88 New Member

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    Thanks for the replay I have a device hooked up the cig socket already and that is the only acc I have the other acc controls te ecu and I don't want to fuse tap that
     
    #10 rock88, Aug 28, 2013
  11. ChapmanF

    ChapmanF Senior Member

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    Here's an idea that doesn't help if you want ACC, but works well if you want something powered only when the car is running (READY). The basic idea is like one of those battery protectors that let you run stuff off the battery until the voltage drops below 11 or so, then shuts off so you don't fully drain the battery. You just change the voltage threshold so it's up slightly above 13. That's above the battery voltage when the car's off, but the nice regulated 13.8 from the DC-DC converter will turn it on when the car's READY. What's nice is you can just wire it right in at the battery in the back of the car, and you don't need to find and tap into some ig-switched circuit to control it on and off.

    The one I built for my Gen 1 is here - mounting location etc. would be different for a c, but the operation should be the same.

    One thing I've thought about adding to mine is a switchable threshold: using a switch and a second zener I could have the option of a lower cutout voltage, like a regular battery protector, for any time I actually wanted to keep some load running for a while with the car off.

    -Chap
     
    #11 ChapmanF, Aug 30, 2013
  12. kevtan

    kevtan Member

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    Hi newbie here . Need some advice I have scuff plate for Prius c which come with light need help from expert here which fuse I can tap to for my scuff/sill plate ? Thanks
     
    #12 kevtan, Aug 31, 2013
  13. ChapmanF

    ChapmanF Senior Member

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    Update: I've found a neat available product that does pretty much exactly what I built this one to do, complete with the improvement: you can set it so that it doesn't turn off right away when you turn the car off, but stays on for up to two hours longer. It monitors the aux battery voltage during that time so it will shut off early if the voltage ever goes below 11.8, so it still makes sure you don't drain the battery.

    -Chap
     
    #13 ChapmanF, Sep 8, 2013
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