4 ms·

Or disconnect the battery (you’ll have to reset the clock, etc., which is annoying).

• ChuckNorris89 4y ago
  Not great advice. Most new-ish cars also store the dinamic engine calibration data in ECU RAM so if you disconnect the battery you can find your engine running harsher next time. So are the values of the headlights auto leveling system and other stuff. You're also risking to reset the radio/media unit security code (on cars that aren't too new but also not super old), which if you got the car second hand and the former owner didn't save the piece of paper it came with and give it to you, tough luck unlocking it.
  • stocknoob 4y ago
    Not ideal to cut power to the entire car, but that happens anyway on every battery swap, no? If you want to get fancy you can isolate the exact fuse and switch just that: https://www.ebay.com/itm/175668177479 https://www.ebay.com/itm/175668177479 Thinking more, given how common parasitic drains are, carmakers should have all non-essential fuses in a separate subpanel section that can be easily switched off/diagnosed.
    • BenjiWiebe 4y ago
      No. Good automotive mechanics plug a little 12v power supply into the OBD port before replacing the battery, to keep the ECU/radio RAM powered.
  • pvaldes 4y ago
    There are systems that can be attached to save the parameters from the car before you disconnect the battery or even to provide electricity to the car while the battery is being checked in another room. Not common to find and most people don't need them, but they exist.