Can I wire in dash cam from double power source?

[Rayyy]

I’d like the dash cam to turn on automatically when I turn the key to ON, but would also like to be able to turn on the cam with the key out, using a rocker switched I installed.

My question is: could I tap into two different fuse locations in the fuse block, and wire them in tandem to the same power wire of the dash cam… so, if I turn the key, that fuse will power up the cam, otherwise if I hit the switch, the other (constantly powered) fuse will activate the dash cam?

Would it cause a problem to accidentally power on both simultaneously?

 

[B-train]

As long as both power and both grounds are together it shouldn't be an different than a parallel circuit. However, using the toggle switch to power it up will backfeed the key on circuit. Depending on what fuse you pull from, could possibly cause issues.

I'd probably just choose one or the other. You could also just make a pigtail that allows the 2 sources you mentioned, but can only choose one at a time.

Another idea to go with your original plan is to put a diode in line with the 12v key on circuit. Then you could use the switched one and not push 12v back to the other circuit.

 

[Rayyy]

As long as both power and both grounds are together it shouldn't be an different than a parallel circuit. However, using the toggle switch to power it up will backfeed the key on circuit. Depending on what fuse you pull from, could possibly cause issues.

I'd probably just choose one or the other. You could also just make a pigtail that allows the 2 sources you mentioned, but can only choose one at a time.

Another idea to go with your original plan is to put a diode in line with the 12v key on circuit. Then you could use the switched one and not push 12v back to the other circuit.

Ahh okay, could I place a diode on each line before the merge just to be sure there’s no backfeed to either fuse?

 

[B-train]

Yes. I think that would do it and keep both separated

 

[MassHoe04]

I just installed a Boss Audio radio head unit and Boyo backup cam from Crutchfield. I used their Ready Harness service, where they made up the plug and play harness to plug the new radio in to the factory harness. Worth the $25!

Anyway, in the process of consulting with the Crutchfield tech, I found out the factory harness has a wire already in the connector that carries a reverse trigger signal from the BCM. There was no need to tap into reverse wires in my tail light assembly or on the tow hitch wiring harness. One of the pins in the factory harness connector for the radio carried the reverse trigger signal.

The Boss Audio head unit also had a wire on the back of the radio marked "Rear Cam PWR 12V+". That was a constant 12v+ feed that was live when ignition is in ACC or run mode. It goes live when the radio is powered on.

This simplified hooking up the backup cam.

With the 12V+ wire for the rear cam on the radio, that allowed the cam to be powered on and viewed without having being in R on the transmission. That is handy for checking on a trailer/load any time you need.
The reverse trigger signal from the radio harness still tells the radio head unit I am backing up and will throw the camera on the screen as soon as you shift to R.

Plug-in harness at the cam. Find a single body/chassis ground in the back. Connect the rear cam 12v+ on the back of the radio to the red wire on the camera harness. Connect video feed RCA jack. Snap in plug and play Ready Harness between truck harness and back of radio head unit.

I am sure Crutchfield tech should help you figure out how to get it the way you want it. Their tech and sales support are top-notch!
Get a few of the Qwik-Tap connectors. Connect multiple wires, no crimping, no soldering, very secure connection.

 

[MassHoe04]

In response to your original set-up question...

I would want to wire a relay (or relays) in with the switch, so that power can only come one way and go out one way.
I would want the power to come on with the toggle when the accessory power is on and the reverse trigger is off.
I think relays would make that happen for you.

 

[Doubeleive]

I’d like the dash cam to turn on automatically when I turn the key to ON, but would also like to be able to turn on the cam with the key out, using a rocker switched I installed.

My question is: could I tap into two different fuse locations in the fuse block, and wire them in tandem to the same power wire of the dash cam… so, if I turn the key, that fuse will power up the cam, otherwise if I hit the switch, the other (constantly powered) fuse will activate the dash cam?

Would it cause a problem to accidentally power on both simultaneously?

your question really does not make logical sense
If you install a toggle switch then as long as it is installed properly it is impossible to "accidentally" do anything
that is the whole purpose of installing a switch to begin with.
for instance
switch position 1: accessory power
switch position 2: constant power
the only thing that could accidentally happen is to leave the switch in position 2 and eventually drain the battery

 

[MassHoe04]

your question really does not make logical sense
If you install a toggle switch then as long as it is installed properly it is impossible to "accidentally" do anything
that is the whole purpose of installing a switch to begin with.
for instance
switch position 1: accessory power
switch position 2: constant power
the only thing that could accidentally happen is to leave the switch in position 2 and eventually drain the battery

Or... You can do it easier @Doubeleive 's way... LOL

 

[Rayyy]

Hmm indeed, wow ya that is a much better plan. I was going to repurpose the switch I had already installed for a different reason, which is just an on/off switch… Although, installing a three position switch makes much more sense, doh!

I guess ideally I wanted the accessory power to be automatic regardless of switch position when the key was ON, but the three switch sounds like the best solution after all.

Thanks.

 

[Rayyy]

@Doubeleive How would I wire that up in the fuse box??

The three position switch has three terminal pins.

So, accessory power to one pin, constant power to another terminal pin… Dash cam positive to the middle pin?