I’ve wired a Viofo Duo in my 2022 Mazda 3. All the cabin panel’s fuses are always powered. I put the black lead of my multimeter on the bolt at the fuse panel and touched both sides of the fuse slot that I’m tapping and they both show power. Isn’t one of these sides supposed be not powered?



I’ve read that tapping a slot the wrong way (backwards) will feed the original circuit’s power (15A) power the additional amperage of the dashcam which sounds really not good, but there doesn’t seem to be a “backwards” for this slot. (I chose this slot because it’s a non-essential powered feature, but I also assume the whole panel is this way even if I wanted to tape something else.)

 

Welcome to the forum

 

You are not giving the proper information i.e. fuse number slot?.
You should be referring to the electrical schematic (at least the ID of the fuse slot) for the fuse system before assuming any tap in for any added accessory first.

 

Sorry. It’s cabin fuse number F5–Power Door Lock passenger side. I don’t know where to access schematics but I also don’t know how to read them. I don’t understand why every video I’ve seen on testing for hot side shows one side powered and one side not but on this car both sides are showing power and what that means for powering both the dash cam and the power window in this case.

 

It sounds like you are attempting to connect a live power wire? Is that what the dash cam install guide recommended? Most are acc active only when the start button is applied in 2 of the stetting's.
The other thing is a fuse is a fuse so if there is power going to it when you test properly there is power on both side of the fuse test slot.
Youtube are generally NOT done by professionals or trained electrical automotive service people. So be aware you follow them at your own risk.

Mazda MAZDA3 owner's manual - StartMyCar

or

Mazda 3 (BP; 2019 - 2024) - fuse and relay box diagram - Auto Genius

I am not suggesting that you copy what I did but...
I prefer in my own personal Mazda to use a piggy back dual fuse connector installed in F__Audio fuse (my number may not be the same for my year and model # as yours? ) that is (ignition power activated) for my dash cams, (2) I also have them on their own fuse rated at 7.5amp to protect the circuit.

 

I went out and checked my Audio fuse slot with the car off and the multimeter reads 12V. My car is a 2022–could our Mazda cabin fuse panels be wired differently?

just for complete description of what I’ve done:
I am using the Viofo hardwire kit which has wires for an Accessory power wire (obviously so the cams turn on and off with ignition) and an always-on Battery wire so I can use Parking Mode when the car is off. In that hardwire kit is a switch that you can set a voltage where if the battery drops below that set voltage, Parking mode is powered off.

I have the accessory wire fed through the firewall grommet and attached to a fuse tap, the fuse being one I checked with ACC off then on—I only measure power when ACC was on. That is engine compartment fuse 18 (“additional circuit protection”, because all other fuse slots I checked all had power with the car off, including things I’d have thought would be unpowered since those features are inactive with the car off).

The “Battery” wire is the one tapped into the driver window cabin fuse slot. In all instances my multimeter black lead touched ground while the red lead touched the metal piece inside the fuse slot.

My main concern, of course, is should I have any worries about which direction the fuse taps are placed since I’m reading voltage on both sides of the fuse slot. Also, I made a video about this installation which I intend to put on YouTube and I don’t want to misinform people if I’ve done something wrong. It started as a video about how to get through the firewall grommet because I couldn’t find info about, then it morphed into a full dash cam install video.