Considering ReelDealEV.com’s Google Analytics number two top search query was “Tesla Model 3 12v battery warning”, we better do our part to pass along the message from Ohmmu.

Support Notice For:

Vehicles: Tesla Model 3, Model Y (Does not apply to other makes/models)

Software Versions: 2021.36.x, 2021.40.x

Support Notice Information

This is an update for customers with Tesla Model 3 and Model Y vehicles, running software versions 2021.36.x and 2021.40.x. 

Below, please find a reset and update procedure that will allow you to update your vehicle to software version 2021.44.x, which should help resolve all or the majority of issues in affected vehicles. Before proceeding, please confirm that the software update 2021.44.x is completely downloaded and ready for installation.

Reset & Update Procedure (Est. Time to Complete: 15 mins)

 1.  If possible, drive your vehicle for ~10 mins prior to performing this procedure

 2.  Confirm that Tesla software update version 2021.44.x is staged for installation (12V alert does not effect this update from downloading to your vehicle)

 3.  Unplug all USB devices in vehicle cabin

 4.  IMPORTANT: Roll window down and leave the driver's door open for the ENTIRE PROCEDURE (Model 3: Also leave passenger side rear door open)

 5.  Open Frunk

 6.  On MCU (Tesla computer touchscreen in vehicle cabin), tap "Power Off" under "Safety and Security" menu and confirm

 7.  Exit vehicle (be careful not to close driver's side door) and lift open Frunk

 8.  Model 3 (All) and Model Y (2020 - Early 2021): Remove upper trim panel in Frunk by pulling up edges gently

 9.  Model Y (Late 2021+ w/ HEPA Filter): Remove the 2x 10mm bolts securing the HEPA filter, remove filter assembly, and then remove upper trim panel in Frunk by pulling up edges gently. You can watch a video of this process here: Watch Video

10.  Locate (DO NOT disconnect yet) High Voltage (HV) disconnect method for your vehicle - see below:

Model 3: Located under passenger side rear seat (to access, slide seat lock tab toward center driver side to unlatch, then lift seat cushion up, remove black foam block, and locate grey plug underneath)

Model Y: Located in Frunk on passenger side above wheel well (red/black connector near First Responder Loop w/ orange tag)

11.  Using a 10mm wrench, loosen the negative terminal of the 12V battery (this is the terminal nearest the drivers side, without a red cover and no fuse attached)

12.  Remove negative terminal -- be careful not to drop lead spacer! Position the negative connector lug so that it doesn’t fall back onto the negative battery terminal.

13.  Disconnect HV

Model 3: Unlock Grey/black header by pinching top and rotating locking arm downwards, then pull up to disconnect

Model Y:  Slide red lock open, then squeeze end of plug while pulling apart to disconnect

14.  Wait 10 seconds

15.  Reconnect HV

Model 3: Reconnect Grey/black header by pushing firmly back into place and then rotate locking arm upwards into locked position

Model Y:  Push together connectors and slide red lock into closed position 

16.  Wait 20 seconds (Don’t need to wait any longer than this)

17.  Reconnect negative terminal lug -- again, be careful not to drop the lead spacer!

18.  Tighten negative lug connector using 10mm wrench

19.  Model 3: replace foam block, then push rear seat down into position firmly, lift up to confirm it has latched

20.  Model Y (Late 2021+ w/ HEPA Filter): Reinstall HEPA filter using 2x 10mm bolts

21.  All Models: Secure top trim panel in frunk by placing into position then pressing along edges to snap together (will hear/feel snap)

22.  Wait for vehicle to reboot

23.  Disable sentry-mode under "Safety and Security" menu

24.  Wait 1 hour (this gives 12V battery time to recharge before initiating update)

25.  Update software version to 2021.44.x