How-To Here's how to safely tap 12v power for add-ons

  • SUPPORT THE SITE AND ENJOY A PREMIUM EXPERIENCE!
    Welcome to Tesla Owners Online, four years young! For a low subscription fee, you will receive access to an ad-free version of TOO. We now offer yearly memberships! You can subscribe via this direct link:
    https://teslaownersonline.com/account/upgrades

    SUBSCRIBE TO OUR YOUTUBE CHANNEL!
    Did you know we have a YouTube channel that's all about Tesla? Lots of Tesla information, fun, vlogs, product reviews, and a weekly Tesla Owners Online Podcast as well!

Achooo

Well-known member
TOO Supporting Member
Joined
Oct 20, 2018
Messages
237
Location
Orange County, California
Tesla Owner
Model 3
Country
Country
The Model 3 doesn't have traditional fuses. If any one of the power lines are shorted or draw too many amps, a digital "breaker" trips. This breaker automatically resets, too. I don't know if the reset happens after a few seconds or if it requires a power cycle, but it eventually resets.

I have done the 12v power tap that's discussed in this thread for a radar detector and I didn't bother disconnecting anything. In fact, I don't know what you'd disconnect if you wanted to. You can take the terminal off the battery, but I believe the rest of the vehicle would still be connected to the 12v source coming from the penthouse.

I'd be interested to hear what anyone else has to say on the subject, but I personally don't think you need to do anything really before working on a 12v line. Of course you should take steps to avoid shorting it out, but worst case scenario just wait for the reset.
You can go into the service settings and power down the car to shut down the computers and nannies. Definitely recommended unless you're prepared for a bunch of errors because you inadvertently removed power from one of the computers...whoops
That doesn't actually remove 12v battery power, but that is not necessary if you are tapping a switched 12v connection.
Thanks fellas! I will just power down the car before working.
 

RyTheGuy

New Member
Joined
Mar 17, 2019
Messages
3
Location
Richmond, VA
Tesla Owner
Model 3
Country
Country
Been searching the forms for about two hours and can’t find the answer to this question. I was installing my emergency lights and tapped into the 12 V connection inside of the area behind the cupholders and under the card sensor. I powered down the car but did not disconnect the battery. This was all done from watching some YouTube videos and shold have worked except that at some point the positive and negative terminals that went to the cigarette lighter touched briefly and sparked. Now after reconnecting the power to the female accessory port it will not work. I’ve searched the web about fuses to find out there are none for this and I’ve tried waiting 4 hours and nothing changed. Any ideas on what I need to do to get the cigarette lighter receptacle working again? If tried plugging in different accessories and nothing my volt meter shows 0. The pic shows the terminals that I removed just before they touched.
c695cf4c-3f84-42a9-b997-4e002ed1bff6-jpeg.23417
 

Spiffywerks

Well-known member
TOO Supporting Member
Joined
Jul 30, 2017
Messages
391
Location
Los Angeles, CA
Tesla Owner
Model 3
Country
Country
Have you tried resetting by holding down steering wheel scroll buttons for about 10 sec i believe? The fuses may reset doing this, but I don’t know for sure.
 

RyTheGuy

New Member
Joined
Mar 17, 2019
Messages
3
Location
Richmond, VA
Tesla Owner
Model 3
Country
Country
Have you tried resetting by holding down steering wheel scroll buttons for about 10 sec i believe? The fuses may reset doing this, but I don’t know for sure.
That was one of the first things I tried. I was thinking it was just for the MCU but thought what the hey but no dice.
 

RyTheGuy

New Member
Joined
Mar 17, 2019
Messages
3
Location
Richmond, VA
Tesla Owner
Model 3
Country
Country
I believe that only resets the MCU. A full car power down can be done from the menu (service tab I believe).
I had the car turned off like you suggested while I was working. I noticed that when the car was powered off if you moved in drivers seat it would energize the systems without pressing the break pedal. It was like the weight sensor were turning the power back on where the message clearly only says to press the break peddle energize.
 

BigBri

Top-Contributor
Joined
Jul 16, 2016
Messages
1,073
Location
Toronto, Ontario
Tesla Owner
Model 3
Country
Country
Been using my Blackvue into the hazard light for near 4 months now and thought I'd post an update.

I've not thrown a single error since installing it. However the car doesn't sleep properly. It does 3.5 hour sleeps followed by 3 hour wakes so its awake near 12 hours a day.

I've decided to undo the install and go direct to the cigarette lighter and not use park mode. I contemplated what would've happened if I had the footage from my hit and run and the answer is nothing. I still would've been at the bodyshop for a week etc. It would've given perhaps my insurance some shot at getting their money back but the cost of hit and runs and uninsured drivers is already baked into the cost of insurance. So I figure I'd much rather let my car sleep its 12-18 hours a day of idle time and preserve my electronics and battery. My outcome wouldn't have changed.

I also want to use TeslaFi again. I love that it'll turn on Sentry for me. My fear of being parked is more about a window getting broken as that sounds like a royal PITA.
 

Vision

Active member
Joined
Mar 18, 2019
Messages
32
Location
NYC
Tesla Owner
Model 3
Country
Country
Just want to post a update. I have a 3/19 built car and that port where Ingineerix mentions in his video is being used by tesla. There is a red wire coming of that middle port. Can I tap into it or should I use the light blue 12v accessory wire?
 

Vision

Active member
Joined
Mar 18, 2019
Messages
32
Location
NYC
Tesla Owner
Model 3
Country
Country
You can tap into that red wire. Ingineer said it's used for a trail hitch, which I'm not using.
 

Vision

Active member
Joined
Mar 18, 2019
Messages
32
Location
NYC
Tesla Owner
Model 3
Country
Country
No idea, but it's a pretty beefy wire. For the newer cars it makes it much easier to tap into that 12v switched power source.
 

Bjptolfnut

New Member
Joined
Jun 8, 2019
Messages
3
Location
Windsor, CO
Tesla Owner
Model 3
Country
Country
My model 3 must be one of the newer builds as the red wire is already in the connector most are tapping into for 12V switched power. Is it ok to unplug the wire that is currently in there and add mine for accessories? Or does it need to stay connected?
 
Joined
Jan 30, 2018
Messages
18
Location
Laguna Niguel, CA
Tesla Owner
Model 3
Country
Country
My model 3 must be one of the newer builds as the red wire is already in the connector most are tapping into for 12V switched power. Is it ok to unplug the wire that is currently in there and add mine for accessories? Or does it need to stay connected?
Can you post a picture of the wire / connector you're referencing? Thanks.


-Shane
 

lairdb

Active member
Joined
May 24, 2018
Messages
188
Location
Earth
Country
Country
I am looking up on the driver's side. I believe that is the 6 pin connector described to connect to. But it appears mine already has a wire in that middle port. Thank you for the response.
Try the position above that, or splice that one.

There's a few things going on:
- Tesla is continuing to update the software, which has (several times) resulted in changes in 12v behavior at various places.
- Tesla is continuing to update the physical vehicle, which has resulted in changes, including wiring harness changes. For older production, both positions did not have wires. (In fact, yours is the first I've heard of.)
- The original video by /u/ingineerix that showed clear images of the bare VCLEFT has been lost; unfortunately, that was our best source of documentation for that connector. My best recollection is that those two positions were labeled "SUNROOF" and "TRAILER".
- /u/ingineerix tested both of those late last year, and at the time, they were safe to draw from and behaved as you would expect a conventional "switched" source to behave.

More recently, /u/travisllado has posted using the upper contact on that same connector to provide switched 12v to his aftermarket audio upgrade. (See picture at the end of this post, taken from his gallery at imgur.com/gallery/WtteZMn ).

So, my guess is that Tesla has populated the red-wire-position in the harness, perhaps to lead toward a hidden other end trailer connector somewhere in the tail area, perhaps for something else. Likely that you could tap that and see how it's being switched; also likely that you could use the other position and test to see how they're switching that. Personally, though, I wouldn't disconnect anything without knowing what it was -- tapping it is more reasonable IMO.


None of this is done from official documentation or recommended practice -- we're all just figuring out what seems to work, and then adjusting when an update changes it. Welcome to the underground.



from /u/travisllado's gallery:
 
Last edited:

JWardell

Legendary Member
Joined
May 9, 2016
Messages
3,821
Location
Boston
Tesla Owner
Model 3
Country
Country
TSo, my guess is that Tesla has populated the red-wire-position in the harness, perhaps to lead toward a hidden other end trailer connector somewhere in the tail area, perhaps for something else. Likely that you could tap that and see how it's being switched; also likely that you could use the other position and test to see how they're switching that. Personally, though, I wouldn't disconnect anything without knowing what it was -- tapping it is more reasonable IMO.
Considering a trailer hitch is now available for the Model 3 (in other countries) I think it's clear they started adding a harness. Perhaps you might find the other end if you peek under the bottom or corners of the trunk liner. Might just be perfect for powering rear audio equipment!
 
Joined
Jun 8, 2019
Messages
3
Location
Windsor, CO
Tesla Owner
Model 3
Country
Country
Try the position above that, or splice that one.

There's a few things going on:
- Tesla is continuing to update the software, which has (several times) resulted in changes in 12v behavior at various places.
- Tesla is continuing to update the physical vehicle, which has resulted in changes, including wiring harness changes. For older production, both positions did not have wires. (In fact, yours is the first I've heard of.)
- The original video by /u/ingineerix that showed clear images of the bare VCLEFT has been lost; unfortunately, that was our best source of documentation for that connector. My best recollection is that those two positions were labeled "SUNROOF" and "TRAILER".
- /u/ingineerix tested both of those late last year, and at the time, they were safe to draw from and behaved as you would expect a conventional "switched" source to behave.

More recently, /u/travisllado has posted using the upper contact on that same connector to provide switched 12v to his aftermarket audio upgrade. (See picture at the end of this post, taken from his gallery at imgur.com/gallery/WtteZMn ).

So, my guess is that Tesla has populated the red-wire-position in the harness, perhaps to lead toward a hidden other end trailer connector somewhere in the tail area, perhaps for something else. Likely that you could tap that and see how it's being switched; also likely that you could use the other position and test to see how they're switching that. Personally, though, I wouldn't disconnect anything without knowing what it was -- tapping it is more reasonable IMO.


None of this is done from official documentation or recommended practice -- we're all just figuring out what seems to work, and then adjusting when an update changes it. Welcome to the underground.



from /u/travisllado's gallery:
Thank you for the response! I will try to get back in there this weekend and see if the pin above it will work.
 

lairdb

Active member
Joined
May 24, 2018
Messages
188
Location
Earth
Country
Country
Considering a trailer hitch is now available for the Model 3 (in other countries) I think it's clear they started adding a harness. Perhaps you might find the other end if you peek under the bottom or corners of the trunk liner. Might just be perfect for powering rear audio equipment!
Yeah, I briefly looked for documentation supporting that, but couldn’t find it. EU owner manual still doesn’t mention, and epg doesn’t show a new connector on the rear harness. Do you have anything that points to details?
 

_Travis_

Active member
Joined
Dec 30, 2018
Messages
94
Location
Austin
Tesla Owner
Model 3
Country
Country
Try the position above that, or splice that one.

There's a few things going on:
- Tesla is continuing to update the software, which has (several times) resulted in changes in 12v behavior at various places.
- Tesla is continuing to update the physical vehicle, which has resulted in changes, including wiring harness changes. For older production, both positions did not have wires. (In fact, yours is the first I've heard of.)
- The original video by /u/ingineerix that showed clear images of the bare VCLEFT has been lost; unfortunately, that was our best source of documentation for that connector. My best recollection is that those two positions were labeled "SUNROOF" and "TRAILER".
- /u/ingineerix tested both of those late last year, and at the time, they were safe to draw from and behaved as you would expect a conventional "switched" source to behave.

More recently, /u/travisllado has posted using the upper contact on that same connector to provide switched 12v to his aftermarket audio upgrade. (See picture at the end of this post, taken from his gallery at imgur.com/gallery/WtteZMn ).

So, my guess is that Tesla has populated the red-wire-position in the harness, perhaps to lead toward a hidden other end trailer connector somewhere in the tail area, perhaps for something else. Likely that you could tap that and see how it's being switched; also likely that you could use the other position and test to see how they're switching that. Personally, though, I wouldn't disconnect anything without knowing what it was -- tapping it is more reasonable IMO.


None of this is done from official documentation or recommended practice -- we're all just figuring out what seems to work, and then adjusting when an update changes it. Welcome to the underground.



from /u/travisllado's gallery:
Hey, actually, that's a mistake. I highlighted the wrong pin. I used the center pin, as other have recommended. Can you tell me when/where you got that image?
 

lairdb

Active member
Joined
May 24, 2018
Messages
188
Location
Earth
Country
Country
Hey, actually, that's a mistake. I highlighted the wrong pin. I used the center pin, as other have recommended. Can you tell me when/where you got that image?
Sure can.

[...]taken from his gallery at imgur.com/gallery/WtteZMn
Looks like that's still the image there. Incidentally, see the above traffic -- it looks like Tesla is now populating that position; if you're updating, you might want to comment on that.
 
Last edited: