Hardwire Dash Cam to Map Lights (4th Gen) - Help

[JohnnyxRex]

Hi all, I have a night dashcam (Anker brand) that I would like to hardwire to my 2005 SR5. I do not have the fancy auto-dimming mirror, but I have noticed that there is a slot at the end of my headliner that I expect is used for the mirror wiring

Upon opening up the map lights, I see these wires:

I plan on tapping these wires and using a $10 12V-to-5V USB converter found on Amazon. Others on the forums seem to indicate success with that. My question is, which wires should I tap for a constant 12V source? Unfortunately I am without my trusty multimeter, and not sure where I should connect.

Alternatively, will going straight to the fuse box automatically cut power when I turn the vehicle off?

 

[taxzz]

I hardwired both of our dashcams to the accessory/key power coming off the radio. Running the anker usb cable in the edge of the headliner and down the A pillar.

This is what I used to wire in for the USB.

https://www.amazon.com/gp/product/B00I3P6QQG/