I'm Confused About Something (Fuse Box - Dash Cam)

I'm looking into installing a Rexing V1 dash cam and want to hardwire it to the fuse box under the steering wheel. I want the camera to automatically turn on and start recording with the truck starting, and turn off when the truck is turned off. I would think that tapping the camera into the fuse box (don't know which port I want to use yet) would pretty much do this, but I've seen mixed responses of people saying the camera will still have power when the truck is off (consequently draining the truck battery) and others saying it will not have power. Can anyone please verify which is true? If it does still have power when the truck is off, then why am I unable to power the windows for example when the truck is off? Also, for anyone who has hardwired a dash cam, which port in the fuse box did you use and why? I'm pretty new to this DIY stuff, but am trying to learn.

Thanks!

 

you need to tap a fuse that is only on when the car is on

 

I’m running a hardwired Thinkware f800pro. It uses 3 wires: power, signal(accessory), and ground. Power and ground were ran to my auxiliary fuse panel I made under the hood and accessory was hooked to the fuse box under driver side dash with an add-a-circuit. It comes on when truck turns on and turns off when truck turns off. Zero issue with drain. Just make sure the add a circuit goes to a fuse that only comes on with ignition such as the cigarette lighter

 

I see. So am I understanding correctly that some of the ports on the fuse box under the steering wheel have power when the vehicle is off, and others don't?

 

Beginner question here: what is the purpose of an accessory wire (is power and ground not enough?), and why did you run power and ground to a different fuse box?

 

correct. the fuses for the auxiliary outlets (cigarette) are only on when the car is on.

 

You can experiment and try a few by just plugging and unplugging the tap a fuse. I just looked at the list of fuses and got it right the first time when I wired my dash cam. In may case if you are under the dash looking at the fuse block, you will see two rows of fuses. I tapped the first one (closest to front) and on the drivers side of the bank

 

Don't remember what the fuse was, but it is live only when the ignitions is on

 

Think of everything as a string of items.

So a positive "hot" wire runs from the battery, to say the positive point of a screw in bulb.

In that scenario, the bulb is always on and you have to unscrew it to break the circuit and turn it off.

Instead, you would run the wire first to a switch, then out the switch to the bulb etc.

That is what is happening in your truck....the accessory switch is what disconnects the power until you turn the ignition to accessory mode.

So, when someone says they want to tap constant on, that means they want the wire to avoid the accessory switch.

When they want to tap a wire that is only powered when the truck is in accessory mode, then they want to use the trucks accessory switch.

You can always add your own switch to either scenario.

Both scenarios of course need a negative or ground wire.

 

Seems simple enough, thanks! Does the dash cam typically tell you what amperage it requires? If I remember correctly I think the fuses under the dash range from 5A to 30A.

 

Dash cam hardwire kit is only like a three amp fuse. They are very low amperage, I actually think less than an amp. I used a 3.5 amp in my fuse tap for the cam. The one I mentioned for the tap I think was only 7.5 or 10 amps, but whatever it was I remember thinking even that was a lot of load for that application.

 

I think I follow. But then, if the cigarette lighter only has power when the truck is in accessory mode, that means that it's fuse is essentially an accessory switch. So why not just tap the camera's power wire to here? Does that make sense?

 

It’s so you won’t have to manually turn the camera on and off, it acts as a signal, when it sees the ignition it will power up the unit and when it doesn’t see ignition it turns it off. And the auxiliary panel under the hood is where all my aftermarket accessories get power/ground from. Eliminates a (excuse the language) fuck ton of add a circuits or wire taps under my dash

 

Ok, this makes sense. The auxiliary fuse box is pretty neat. So because this is my first aftermarket accessory that requires any wiring and for simplicity purposes, couldn't I just tap the camera's power into say the cigarette lighter fuse port and secure the ground wire to the bolt that connects to the chassis? This should theoretically turn the camera on/off automatically when the truck's accessory mode is turned on/off, correct?

 

I have one similar to what txtaco87 did as well for most of my wiring. I only have a tapa fuse for my camera as that was the first mod to my truck. He has a larger blue sea fuse block then I do, as I only went for the 6 circuit one with a 100 amp breaker. I added extra USB ports and 12 volt outlets to my truck and all run through that under the hood setup. I installed a 4.6 amp bluesea dual USB in one of the blank center dash lower panel spots next to the (ECT switch) that I left live all the time for running things like a tablet when I need maps. The 12 volt in the bed of the truck and the USBs I put in that back of my center console for backseat passengers are all run through relays that are triggered when the ignition comes on so I don't have to worry about leaving something plugged in. I also have a light bar that I don't want accidently on if the ignition is off so that switch is also tied in to where the light bar cannot be turned on without the ignition on. With relays you don't deal with high power at the switch as they take only milliamps to switch them. Again for the camera though just a tapa fuse makes it really easy. The ground can be pretty much anywhere under your dash. I just ran the grand right in front of the fuse block under the dash (towards firewall) where there was a grounded spot

 

Yes it should. Most of the cameras only use a 2-3amp slow blow fuse so it doesn’t pull much power. If for some reason it does not work, you can easily hook power to battery, ground to battery or body under the dash, and use cigarette lighter for the accessory signal wire

 

Sounds like the directions were for 1 wire to be Ground, 1 12V constant, and 1 Accessory, you can choose the cigarette lighter fuse for your accessory power no problem.

 

Thank you guys for your input! I'll update you on how it goes!

 

Well a device can have multiple switches.

Example your window up down switch.

1st switch = accessory power switch on ignition.
2nd switch = the actual button you use to open/ close.
3rd switch = your in line fuse.

Power cannot flow past a switch that is in an open position. So.....in order to open the window, your fuse must not be blown, your truck must be in the accessory ignition mode, and you have to push the button. Simply pushing the window button does not do anything if the fuse is blown, or the truck is not in accessory mode.

In the example you gave the trucks accessory switch is upstream oforhe energy current, thus preventing power from flowing downstream to the iniline fuse, unless the truck is on .

It can get confusing because you may have a fuse upstream, then a switch, then another fuse, then a device, and yet another fuse.

Such is the case with many 12v cigarette recepticals wired to accessory with a 12v plug with a fuse in the plug itself. Litterally three fuses would need to be checked.

 

OP, check this thread out for a college level education on wiring in general and specifically on adding an aux fuse box..
https://www.tacomaworld.com/threads/diy-build-and-install-a-bussmann-rtmr-fuse-relay-block.399454/