Searching for a 12V switch wire in lift gate

[Z-Thrizzle]

I'm installing a rear-view camera and I would like to tap into a 12v switch wire. I checked some of the wires but didn't find it. That was my first time using a volt meter...so who knows maybe I was doing something wrong. Figured I'd check in to see if someone knows.

 

[mightymavkev]

Z-Thrizzle, there may not be a "switched" 12V source back there. Should be 12V switched feeding the wiper motor, but that may also be "wiper switch" switched and not just ignition. License plate lights / tailgate light / Tail lights are all 12v constant or switched off of their respective switches as well. Mine has a power lock rubber covered push switch up under the right side of the door latch. But that's probably unswitched as well.

Honestly, there may not be a "ignition switched 12V" wire in the tail gate as the car doesn't need one back there.

Is the power outlet in the cargo area switched or unswitched? You'd have to run a wire up the inside and through the wiring grommet at the top of the door by the hinge to use that, but that's where I ran my camera wire and it wasn't that bad.

Does your camera require the power and ground to be wired locally? On mine, the camera wire - which is very small - carried signal as well as power and ground from the head unit and that's where I tapped into the power and ground. Thinking you have to run a signal wire to your head unit regardless (unless your camera is wireless - which would be cool) so maybe the power and ground are part of that wire and you can just do that hook up under the dash.

I realize not all cameras are the same though. I'm just saying that's the way mine was.

 

[Z-Thrizzle]

Yeah it doesn't really make sense to have a 12v ignition back there. The camera is wireless so I won't be running wires to the front. I guess I'll just wire it to the reverse light. Since I could not find the reverse wire to activitate he camera by the radio I installed a switch. Thought it would be cool to turn on the camera feed whenever I wanted.

 

[xxxmonoxidechil]

alot of the switched circuits on the newer mazda's are also switched Grounds. it took me a few hour's of messing around before i figured that out in my mazda6. i was losing my mind until i figured that out.

 

[mightymavkev]

Yeah, if the reverse light is negative switched vs positive switched it probably wont work. Digital voltmeter should tell. I dont have much experience with negative switched circuits though.

 

[xxxmonoxidechil]

its the same as anything else. just instead of the power being the turn on lead. the ground is. but when your hunting around for a live wire looking for a positive switch, it can mess with you when it ends up being a grounded switch. lol

 

[table5511]

Well, as most vehicles nowadays have pre-wired fog light plugs/pigtails just sitting behind the bumper.... this may also be the case with the CX-9 power liftgate plug. I can't see Mazda putting in an entirely different interior wiring harness just for that one option.

This plug/power source would likely be located in the driver side quarter panel behind the trim panel.

Also, what about the 12v accessory outlet in the quarter panel? just tap into that and run it into the liftgate? (unless for some reason your cx-9 doesn't have an accessory 12v outlet back there)

 

[Z-Thrizzle]

Well, as most vehicles nowadays have pre-wired fog light plugs/pigtails just sitting behind the bumper.... this may also be the case with the CX-9 power liftgate plug. I can't see Mazda putting in an entirely different interior wiring harness just for that one option.

This plug/power source would likely be located in the driver side quarter panel behind the trim panel.

Also, what about the 12v accessory outlet in the quarter panel? just tap into that and run it into the liftgate? (unless for some reason your cx-9 doesn't have an accessory 12v outlet back there)

Funny that you say that because I've been finding that Mazda uses different wiring harness depending on your options. For example I pretty much have a base 2011 CX-9 Touring with no options.

The aftermarket radio harness has the connection pins set so that it's plug n play. The reverse wire pin is there but not in the oem harness becuase I have the base radio.

I wanted to hardwire my V1 by the rear-view mirror after seeing others tap into harness that is there for an option (I forget). From seeing pics others have posted I can see the hole where the harness is to be mounted but no harness.

Yup and you guessed it....I also have no harness for lift gate control.

 

[table5511]

Wow, that is really shocking to hear! I can't believe they put in a different harness based on options, you would think it would save money to have one harness for all applications. I can only imagine how much of a pain it would be to bury a 12v wire in the car going from the engine bay to the back.

 

[Z-Thrizzle]

I'm not looking forward to running wires through the car but the wireless transmitter flickers a lot. The signal was fine when I tested it out but that was done with the transmitter and receiver close together. So I'm going to run the wire for video from the lift gate to the center console. While I'm at it, I might as well run a 12v ignition wire through