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Under-Hood Fuse Box/Position Source of +12V at "READY"?

Discussion in 'Prius v Technical Discussion' started by Air_Boss, Mar 1, 2013.

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    Offline Active Member

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    I don't see offhand why this old thread has been revived but fuse #28 in the engine compartment fuse box of our 2012 Prius v is hot only when the ignition system is in READY mode. A photo showing the fuse tap I inserted into the fuse receptacle to power a DRL-2P kit is in a PDF attached to post #1 in the following thread: WebElectric DRL-2P installation into 2012 Prius v | PriusChat
     
  2. Air_Boss

    Air_Boss Senior Member

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    Our v Five shows a DMM +12.53V on Fuse #28 with the car OFF ... as well as at READY.
     
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    Does your Prius v Five have the Advanced Technology Package like ours? I wonder if there is a difference. The circuit at fuse 28 (for "Inverter and converter") in our Prius is dead as a doornail when the car is powered off.

    I didn't come up with the idea of powering a DRL kit from fuse 28. I was just following the lead of others on this forum who had installed DRL kits and used a fuse tap into fuse 28 to power them. The Webelectric DRL kit on our Prius has been working great for over a year and I don't see how the DRL could be shutting off when the car is powered off if fuse 28 had constant 12V power.
     
  4. Air_Boss

    Air_Boss Senior Member

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    No
    I understand your setup. Ours has no ATP, just a vanilla v Five. And +12V on the base of Fuse #28 when OFF.
     
  5. Air_Boss

    Air_Boss Senior Member

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    Well... Is there a condition between "OFF" and "READY"?

    Because now I'm getting a DMM +12.93V on #28 at READY and -0.00 upon lifting hood after opening doors, whereas I was previously getting +12.53V with the car thought to be OFF.
     
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    Offline Active Member

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    Yes, there appears to be an electrical system state between Off and Ready. Have you noticed the noise from the braking system "charging" when you open the driver door when the ignition is Off?

    Also, fuse 28 remains hot for a couple of seconds after the ignition is turned off.
     
    #26 Offline, Sep 2, 2014
    Last edited: Sep 2, 2014
  7. Air_Boss

    Air_Boss Senior Member

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    Yes and yes.
     
  8. Air_Boss

    Air_Boss Senior Member

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    Go figure. It turns out that if the relay harness you bought has an open in the 'ground' lead, nothing works as it should.

    One splice later, finally got the LED fogs operating as DRLs, using inverter voltage exceeding +13.2V at fuse #28 as the relay trigger.
     
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