Dead 12-volt start battery
Dead 12-volt start batteryEarlier, August of 2024 to be exact, we got a panicked call from a friend whose car, a Tesla Model Y, was giving her real headaches. It turned out to have a dead 12-volt start battery.
A number of messages were being displayed in a seemingly random fashion on her instrument panel, but one indicated a problem with the 12-volt battery. Her car is electric, so when she seeing battery caused the panic, but in effect all EVs have 12-volt batteries too, needed to start the electronics. We posted on this at our website and you can see it here.
She was fortunate to have enough power left to actually get in the car. However, no Tesla models have mechanical keys available to accomplish this if the 12-volt battery is actually dead.
The video demonstrates how to get inside a Tesla if the 12-volt battery dies so that the battery can be charged or replaced. The instructions are in the owner’s manual, which inside the locked car on the center screen.
Each model has are two wires, red and black or positive and negative, available somewhere at the front of the Tesla to connect to. The Model 3, Model Y and Model S give identical access behind tow eye cover in the bumper on the left side. The gif file to right is a pretty good demo, but its more difficult in practice.
We added the Model X and Cybertruck as well. You can see the video here on our Tesla page here or on YouTube here.
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Remember that only proper service and repair procedures will ensure the safe and reliable operation of your car. In addition, proper safety procedures and precautions, such as the use of safety goggles, the right tools and the equipment should be followed at all times to eliminate the possibility of personal injury or improper service which could damage the vehicle or compromise its safety.
These posts are for information sharing purposes only, and should not be used in lieu of an OEM service manual or factory authorized service procedure. We are not in the auto repair business nor do we publish automotive service manuals. Nothing we include on these pages and posts has been reviewed, approved or authorized by any vehicle manufacturer.
Technology is always changing and what is current and accurate today may be literally out-of-date and inaccurate tomorrow. And when it comes to the current state of flux in the auto industry, nothing is more true.
The author has 25 years of automotive experience and has assembled the most extensive collection of symbols and warning lights anywhere (over 1,000!) and can help you open and start any keyless start car with a dead key fob battery. BA, St. Joseph’s College, ME: MS, Rensselaer Polytechnic Institute, NY
There are three basic locations to try, as shown in the image, but experience tells us you might just as well skip to the last one. The first, top to bottom, is to simply drop the key fob into the cup holder. If this fails, hold the key fob against the front of the console, as we are doing in the image (second). There are several places that can be tried in this case alone.
If all these fail, the next recommendation is to remove the battery from the fob and run through the options again. As it happens, this is exactly what we had to do with the Model X we had and we landed at the base of the console before the car recognized the fob. That location, with the key fob resting in place, is shown in the second image. The fob was recognized at last and we were able to operate the car.
If you were given a key card, place it against the left side of the of the space at the front of the center console just below the screen, as shown to the right. The vehicle will recognize the card, the instrument panel will come to life and the car will be ready for action. Don’t lose the card!
If your mobile phone has gone dead or is missing, place the key card on the center console behind and between the two cup holders. The car will recognize the card and will allow it to be driven.
In the earliest versions of the Model S, the back of key fob is to be placed against the passenger side front fender, somewhat below and to the right of the emblem, as shown in the image. When the fob is recognized, the door handles will extend as they do normally.
The concept is the same in the newer Model S, but the location is changed. However, it remains on the passenger side. Place the key fob near the base of the passenger side windshield wiper. The image to the right shows the exact spot that worked in the model we tested, and we tried several. Then press the driver’s door handle. The handles will extend if it is recognized, but it took a full 20 seconds in the car we tested. Try repositioning the fob if this fails. If it continues not to be recognized, try removing the battery and go back through the process.
Tesla’s Model X uses an entirely different back up location. There again is no hard key or key cylinder. In addition, the door handles do not extend in normal operation as with the Model S. The mirrors will extend when the key fob is recognized.
To get in, the key card is placed on the door frame between the front and rear doors on the driver’s side and just above the bottom of the windows, as shown. As with other models, the mirrors will extend inviting you inside. The vehicles can be locked this way as well.