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Dashcam install - Best Fuse to Tap for Always On + Accessory Power?

Discussion in 'Gen 3 Prius Accessories and Modifications' started by gunn, Jun 18, 2019.

  1. gunn

    gunn Junior Member

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    Hi:
    I'm upgrading my dashcam in my 2014 Prius 3 to a VIOFO A129 DUO (dual cam) and one feature that this new one has that my old one didn't was a parking monitor function.

    In order to implement this feature, I need to hardwire the dashcam to get always on power (instead of just using the USB plug to get ignition on power). The little box that the kit comes with also includes a voltage level cutoff -- so if the 12V battery drops below 11.8V, 12V, 12.2V, or 12.4V it will cut off.
    Setting Up with the VIOFO 3-Wire Hardwiring Kit | Dash Cam How To Installation Guides — BlackboxMyCar

    I've searched the threads and noticed that some people recommend tapping into the dome light, opening up the rearview mirror to access the wiring inside for the homelink, the wiring behind the cigarette adapter to get the necessary constant and ignition-on power.

    Q: If I go with the fuse-tap option, which circuits have constant or ignition on power that I can tee off of? This is probably the cleanest way to install.

    If not, what's a better backup plan? I suspect it would be the cigarette adapter wiring under the center console but I'm open to suggestions.

    Right now, I plan to just run the wiring for the rear dashcam and use the stock USB cable I already have in place from the previous setup (runs from in front of the rearview mirror, down the driver's side a-pillar, underneath the steering column, and back to the USB plug in the armrest.
     
  2. Fifen

    Fifen Member

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    I don't know much about wiring. But to find out which fuses turn on with ignition and which are constant I recommend getting a multimeter and checking for current from the fuses with the car off vs on. Don't forget that the fuse has 2 sides. A active power side and then the other side sends power away (I might be wrong on the other side)

    Posted via the PriusChat mobile app.
     
  3. ThatDudeOrion

    ThatDudeOrion Member

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    There’s a fuse box down by the ebrake pedal, mine is 3 columns by idk 12 rows the middle column is always hot and the outer column is switched hot, or maybe vice versa, but anyways mine had plenty of empty unused fuse slots and I just put my add a fuses in those spots. It’s easy to verify with a multimeter. And like the above reply stated you need to remember that orientation matters when using add a fuses so if it doesn’t power up like you expect, flip the add a fuse legs 180.
     
  4. Grit

    Grit Senior Member

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    If your 12v battery drops to 12.4v, other problems may arise. But if you install a bigger battery like Raytheeagle then you'll be set, and probably be poo'd poo'd on for installing a bigger battery like him.
     
  5. gunn

    gunn Junior Member

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    Thanks for the heads up. I wasn't sure if there was power to the unused points on the fuse box. I have a multimeter so I'll check that once the right fuse taps come in from Amazon.
     
  6. gunn

    gunn Junior Member

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    1) Exactly what other problems might arise if the voltage drops below 12.4V? Are you speaking from experience? I just installed the VIOFO after work and it works like a charm with front and rear cameras + WIFI support (in the event of an accident, I figure being able to show/download videos from the camera via WIFI will be helpful to show a cop vs viewing it on a tiny screen)

    - From my knowledge of other cars, the most load required from a 12V battery is to start the engine and that's all about the amps. My V8 powered track car uses a much bigger battery whereas the Prius battery is more like what you'd find in a lawnmower.

    According to this quora answer, a Prius engine is started by the motor/generators to get things moving. This is fed not by the weenie 12V battery but from the NIMH battery pack.
    How does a Prius starter work? - Quora

    2) Do you have a link to the post you are referring to for raytheeagle AND/OR a link to exactly which 12V he upgraded to? I searched all posts writted by raytheeagle and a) he didn't seem to write a specific thread on it and b) he has a ton of posts referring to battery (because its a prius and every third post is about batteries).
    - My battery is 5 years old now (Purchased 2014) so its probably on its last legs (even though it isn't subjected to crazy temp swings in the Bay Area.

    2b) Why do people poo poo a larger battery and why should I care what other people think for installing a bigger battery? I DD a frigging appliance for gods sake. FWIW, this is the most boring, reliable car i've ever driven. I'm shocked at how little I've done to it over 125K mi.
     
  7. egn83b

    egn83b Junior Member

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    Go buy a fuse tap on amazon for your interior fuse box. I have aftermarket heated seats i use a fuse tap to make sure they never run while the car is off.

    Posted via the PriusChat mobile app.
     
  8. cnc97

    cnc97 Senior Member

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    No matter which side you connect to with an add a fuse, it will be fuse protected by the fuse made into it. The orientation only matters whether it is protected by the fuse tapped into as well.
     
  9. ASRDogman

    ASRDogman Senior Member

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    The fuze should go on the POSITIVE side. Current flows from positive to negative.
    If you connect on the negative side, you'll fry the electronics up to the fuze.
     
  10. Fostel

    Fostel Member

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    I just tapped my hardwire kit yesterday. Works flawlessly.

    Yellow (ACC) --> WIPER RR (15A)
    Red (Battery) --> P/OUTLET (15A)
     
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  11. DimitrisTS

    DimitrisTS Junior Member

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    Nice!
    Post some photos with the front and rear camera's in place!
    I plan to buy this camera also and I wonder if the rear cam cable is long enough to get to hatch door.
     
  12. Fostel

    Fostel Member

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    No pictures of the whole setup as yet but I took some photos during the installation.

    That's the fuse box cover, marked red and yellow.

    IMG_20190902_084730.jpg
     
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  13. QuantumFireball

    QuantumFireball Active Member

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    I've just ordered an A129 Duo with the hardwire kit and fuse tap. Any recommendations regarding installation and wiring? My biggest concern is how to run it through the A-pillar as there's an airbag there.

    I feel there's big enough gaps under the door sill trim to run the cable for the rear camera, but haven't really looked at anything else yet. My car is RHD so the fuse box is under the glove box.

    With the hardwire kit, did you set the cut-off to 12.4V?
     
  14. Attila Fekete

    Attila Fekete Member

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    Although the installation manual for Homlink mirror is for LHD, it will help to remove the A pillar and about the wireing.
     
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  15. QuantumFireball

    QuantumFireball Active Member

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    Thanks, the diagram for the A-pillar trim looked a bit bewildering but it wasn't that hard in the end, just the central retaining clip which requires rotating is a bit tricky.

    I heard a few people mention this but it doesn't appear to be true (not on mine anyway) - I found fuses on the outside rows that were constantly live as well as the centre row. I did use a couple of spare fuse slots though and they seem to work OK once I found one that was actually ACC-only.

    I would recommend a multimeter if you're trying to do this - it makes it a lot easier to probe the fuses to see what's live, and for finding a good ground.
     
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