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Mazda 3 2021 Preferred 2.5 AWD
1 Posts
Discussion Starter · #1 · (Edited)
Not a car girl (so may sound dumb, sorry about that), but I am trying to hardwire Thinkware TW-FA200DH dash cam onto my 2021 Mazda 3 by myself and would appreciate advice from the experienced.

The hardwiring kit comes with a Constant wire and a ACC switch-only wire.
However, I tried all of the fuse box next to the driver seat with a circuit tester and they are all constant.
So right now I am connecting both wires to an add-a-tap with two extra 10A fuse I bought, into an empty fuse box, as such:


For the ground wire, I just tape it to this nut below the driver seat as I don't have a wrench 馃槄

The camera still works but it's now constantly recording non-stop.

Any advice how I can find a way to tap my ACC wire to ignition only fuse?

I tried looking for answers here and it seems the switch-only fuses are in the engine compartment?

I read this post about the wiring loom for OEM auto dim mirror, but I couldn't remove the A-pillar (It seems impossible to remove without breaking something?!)

824 Posts
Since you're already working in the kick panel area and have an add-a-tap, I'd tap this white wire used for the OEM wireless charger as your switched ACC:


ETA: The trick for the A-pillar (and kick panel) is to first pull out the seaming welt:


Manual also mentions cutting this:


Also ETA: I'd work out a proper ground so you don't have battery draining or other complications from using tape. One candidate might be to use another add-a-tap on the black wire from the lighter socket in the center console.

36 Posts
I'll second that suggestion. none of the fuses in that internal fuse box are switched, they are active all the time.

You can get dashcam specific voltage controllers that will cut off the camera when the battery voltage drops after stopping, but in my case at least it makes the camera shut down randomly and is unpredictable.

Get a small size wire tap (wire taps are sometimes also called t-taps and some other names) and that will let you easily tap into the white wire shown in the above post, that will switch on and off with the ignition properly.

And definitely get or borrow a socket wrench to put the wire onto one of those bolts near the fuse box properly.

Mazda "E" Division
1,282 Posts

A piggy back fuse tap would be the easiest and you can plug into the 7A radio slot and it will turn off with ignition

200 Posts
All the fuses in the internal fuse box are hot. There's a harness in the a pillar where there's a constant 12v, ignition switched wire, and grd you can tap into. That's how I wired mine. Search through here a few of us have written guides.

81 Posts
I have used tap to the dimming center mirror. Works when ignition is switched. There is a single connector where green cable is 12V switched and black is gnd. After that I have used step-down convertor from 12V->5V with an USB slot and everything is now well hidden inside the black plastic housing behind the mirror. Only an USB cable sticks out from the mirror joint area.
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