Proper 12v, Accessory, and Ignition wires

[ecko04]

I was a MECP Master Certified Car Audio Installer for Circuit City and Best Buy/Geek Squad in a past life. I picked up my Stinger a few weeks ago and it made me cringe to see people grabbing power for dash cams from their OBDII ports and other random places. Grabbing power from the OBDII is an issue, because not only is it current limited, there's also issues with resolution. For example, if you are powering a dash cam but also logging, there will likely be a delay in data flow making fine tuning and troubleshooting more time
consuming and cumbersome than it otherwise should be. Not to mention you have a dongle running out of the OBDII of you car, which is just not cool.

So I figured while I was installing my dash cam and radar detector today, I would grab some pics of the proper locations to grab 12v constant, switched accessory, ignition, and a proper ground.

These wire colors are the same for the 2.0 and the 3.3, at least in the US market. Not sure about abroad, so you folks should meter these wires first. Granted, if you are connecting any component that receives a signal (i.e., dash cam or radar detector), the worst than can happen is that it will not power on or you power to say the starter wire and your device only powers on when the car is starting or you connect to the wipers and your device only powers on when the wipers are off.

The driver side knee panel is held in place by 2 Phillips head screws and a side panel secured by clips. Remove the fuse panel cover, and while using your hand push against the side panel and use a nylon panel tool to release the clips. Then use a shallow screwdriver to remove the 1 screw. Use a pik tool to release the cover to reveal the screw to the bottom right. Gently, but firmly pull the panel to remove the entire kneel panel. Be sure not to pull too hard as the OBDII wiring will still be connected.

Once you do so, you'll be greeted with this beautiful face:

The thicker gauge white wire being held by my pik (pin 3 in the black 4 pin connector) is 12v constant (i.e., battery).

Next up is accessory. Switched accessory provides 12v whenever the car is in accessory mode or running. This is the wire that most components (i.e., dash cam and radar detectors) are connected as opposed to the OBDII port and lighting circuits. There will be some felt tape covering the connector but it is easily removed with a pik.

In the red 58 pin connector, pin 21 (thin gauge white wire) is the 12v switched accessory wire.

And just because I was down there, here is the ignition wire. This wire goes to 12v when the ignition is in the run position. In the red 58 pin connector, pin 1 (thin gauge red wire)

You can feel free to use in-line fuses with any of the above wires, it's a good practice to do so in case of a voltage spike for whatever reason, your accessories won't get fried, but if that happens the accessories are the least of your concerns.

A decent ground would be the 12mm bolt next to the fuse box located here.

Wire everything in and tape everything back up.

Put your knee bolster back into place in reverse order, don't forget about the screws.

Check out your work, you're done! Congrats!

 

[MrSmoofy]

Nice work but I would add that if you only have a Radar Detector search for those threads and tap into the switched power at the mirror super easy and clean.

 

[ecko04]

Nice work but I would add that if you only have a Radar Detector search for those threads and tap into the switched power at the mirror super easy and clean.

Yep, mirror taps are fine but those also share the same circuitry and they’re low amperage and shared with the homelink. I also had one and I didn’t go with that option.

 

[Kazz]

Quite a clinic - on how to get power for aftermarket accessories and on how to make a how-to post! Very well done! Great info!

 

[celwin]

Now that is how you write a DIY tutorial. Idiot proof.

 

[turboAWD]

Any info on which of those empty fuse blocks can be used with add-a-circuit type connectors?

 

[ZyroXZ2]

Any info on which of those empty fuse blocks can be used with add-a-circuit type connectors?

The inside of the fuse cover has a fuse layout diagram. The "power outlet" ones are the ones you can use with add-a-circuit fuse connectors. Flip the main switch in the middle to off before you do it, of course.

 

[Ed B]

The inside of the fuse cover has a fuse layout diagram. The "power outlet" ones are the ones you can use with add-a-circuit fuse connectors. Flip the main switch in the middle to off before you do it, of course.

Note that it seems they changed the fuse labels, and possibly the purposes? Notice in the above pictures that where your "power outlet" fuses are there are now a "spare" 20A fuse and a 10A "charger" fuse. I wasn't able to find any that were "switched" with power on or accessory. I tried some obvious choices (media Amp 25A, sunroof 20A, media1 -- I think it was -- 10A) and some not obvious ones (luckily I didn't trigger the airbag, oops). All of the things that only work with power on or accessory seem to be switched after the fuse. This may be good for retaining settings in the ECS module I installed, don't know for sure.

 

[ZyroXZ2]

Note that it seems they changed the fuse labels, and possibly the purposes? Notice in the above pictures that where your "power outlet" fuses are there are now a "spare" 20A fuse and a 10A "charger" fuse. I wasn't able to find any that were "switched" with power on or accessory. I tried some obvious choices (media Amp 25A, sunroof 20A, media1 -- I think it was -- 10A) and some not obvious ones (luckily I didn't trigger the airbag, oops). All of the things that only work with power on or accessory seem to be switched after the fuse. This may be good for retaining settings in the ECS module I installed, don't know for sure.

Since I moved from a 2018 to a 2019 and have found a lot of small changes, I'll open the panel up when I get a chance and see what it looks like. I know on my 2018, it was pretty obvious as there were two fuses clearly labeled as "Power outlet".

 

[MrSmoofy]

On my 2019 GT2 for my Radar Detector, I tapped into the wires at the Mirror for switched acc

 

[Berzerker]

My 2018 has multiple empty fuses that supply either switched or constant 12V power. You can buy a fuse to pin to USB converter, no need to tap into any wires.

"Power outlet" 20A I believe is a switched port where it will turn off after a few minutes of the car being off, while the unlabeled one above it is constant 12V.

 

[ecko04]

My 2018 has multiple empty fuses that supply either switched or constant 12V power. You can buy a fuse to pin to USB converter, no need to tap into any wires.

"Power outlet" 20A I believe is a switched port where it will turn off after a few minutes of the car being off, while the unlabeled one above it is constant 12V.

I won’t even begin to go into why you don’t want to add fuses to a fuse box where the fuse wasn’t originally there and make assumptions for what amperage that unused circuit can reliably hold.

 

[MrSmoofy]

IF your installing a radar detector go look at that thread about taping into the mirror wire harness that's what I did so I didn't have to run any wires anywhere.

 

[ecko04]

IF your installing a radar detector go look at that thread about taping into the mirror wire harness that's what I did so I didn't have to run any wires anywhere.

Agreed. 12v ignition right at the rear view mirror harness for a radar detector.

For others who plan to run multiple devices like a radar detector and dash cam that will record 24/7, see OP.

 

[Berzerker]

I won’t even begin to go into why you don’t want to add fuses to a fuse box where the fuse wasn’t originally there and make assumptions for what amperage that unused circuit can reliably hold.

Please do explain, because I've never heard of this. Clearly it was meant for something, since there's live power running through it.

Besides, fuses have to be rated for at least 5A and there's no way these devices are pulling more than 25W of power at a time. Use a low-amp (5A) fuse so it blows at the slightest hint of overcurrent and you'll be absolutely fine.

Splicing and tapping into wires is arguably more dangerous since you're pulling more current over what the line was originally designed/meant for, especially without increasing the amperage rating on the fuse that connection is for.

 

[ecko04]

Please do explain, because I've never heard of this. Clearly it was meant for something, since there's live power running through it.

Besides, fuses have to be rated for at least 5A and there's no way these devices are pulling more than 25W of power at a time. Use a low-amp (5A) fuse so it blows at the slightest hint of overcurrent and you'll be absolutely fine.

Splicing and tapping into wires is arguably more dangerous since you're pulling more current over what the line was originally designed/meant for, especially without increasing the amperage rating on the fuse that connection is for.

This isn't meant to serve as a comprehensive explanation for 12v vehicle electronics so I will spare some very important details.

However, there's power running to almost every connection point on the fusebox. The reason for actually is due to the design of the fusebox and the wiring on the back of the fusebox that supplies current. So yes, while there's live power running to it, that doesn't mean that the wire supplying that power, once again on the back of the box, is suitable for the load that you are introducing by adding fuses to it. Additionally, you do not know what vital system component (BCM, ECM, etc.) is also sharing current with that same circuit for which you are adding.

Splicing into existing wires is a long proven method od accurately integrating components into a vehicle where the electrical load is well established (i.e., closed system). Furthermore, you are not adding to the existing load, you are simply sharing the existing load (i.e., no additional current is being requested). Additionally, adding to the current system allows an installer to accurately assess the gauge of wire being used to determine if the circuit was designed for the load (i.e., the blown fuse will be easily located). Moreover, integrating with the current wiring allows an installer to know which critical vehicle systems are being interfaced with, which makes troubleshooting much easier as these are systems that were already designed with that particular trim level in mind (i.e., system load). Finally, you never want to increase the amperage of which a circuit was designed, which is why when interfacing with an existing circuit the load being drawn, as defined by the fused connection, is less than original design therefore never adding to the load and sharing current at a lesser amperage. When you add a circuit, you are adding amperage to a circuit that was not established and therefore run the risk of, at the very least blowing a fuse, or at the worst, if the fuse is faulty, damaging a critical component that will require a wire trace or something catching fire.

Hopefully, this is a good enough explanation from someone who did this for a living for a while.

FYI, fuses do not "have" to be rated for at least 5 amps.

 

[namja]

So...clearly its not idiot proof cuz I'm an idiot:

I want to hardwire my Thinkware F800 Pro dash cam for parking mode - suggested place is I/P-B pin #3?
I want to hardwire my Uniden R7 radar detector only when engine is on - my options are 1) using slots in mirror (ignition and ground slots); 2) accessory slot

is that right?

 

[ecko04]

So...clearly its not idiot proof cuz I'm an idiot:

I want to hardwire my Thinkware F800 Pro dash cam for parking mode - suggested place is I/P-B pin #3?
I want to hardwire my Uniden R7 radar detector only when engine is on - my options are 1) using slots in mirror (ignition and ground slots); 2) accessory slot

is that right?

I wouldn't use accessory at the I/P-B. Accessory drops below 12v during the start/stop mode. I'd stick with ignition to provide consistent 12v when you're driving. Otherwise, yes, you're correct.

 

[namja]

I wouldn't use accessory at the I/P-B. Accessory drops below 12v during the start/stop mode. I'd stick with ignition to provide consistent 12v when you're driving. Otherwise, yes, you're correct.

Now I'm getting more confused lol.

The thicker gauge white wire being held by my pik (pin 3 in the black 4 pin connector) is 12v constant (i.e., battery).

Isn't this the I/P-B pin #3 that I was referring to? What do you mean it has accessory! I thought accessory was only the "21" pin on the 58 red.

To clarify, here's what I was proposing:

 

[ecko04]

If you want to supply constant 12v, you’ll interface with it.

If it has a decent battery or a mode where it only enables when motion is detected based on the battery then you can go with ignition.

If there’s no internal battery then you only have 1 choice if you want parking mode to work and that’s 12v.