[HarryTee]

I've heard that some car settings can be reset by disconnecting the battery. From which terminal? Or would there be no difference, whichever terminal is disconnected?
Thanks,

[im_an_alien]

Neg first to disconnect... When reconnecting, pos first

[Billfitz]

Everything I've seen says negative. The logical reason for that is if you put a wrench or driver on the positive terminal and touch it to the chassis with the negative in place you'll get a very unpleasant result. As for the car settings, anything stored in iDrive memory isn't affected by disconnecting the battery, as the memory is non-volatile. You may have to reset the clock, but even that will reset itself if you have nav. The main reason to disconnect the battery is if you unplug some items, the seat belts or air bags for instance, while the battery is connected that can cause fault codes to be thrown, and the only way to clear them is with an OBD diagnostic and repair tool.

[HarryTee]

Thank you all! Very informative.

[Gen13 F36]

If your in UK ... you probably have to do the opposite

[dmaxdmax]

Originally Posted by Gen13 F36

If your in UK ... you probably have to do the opposite

Haha! In Australia they need to install the battery upside down.

[Billfitz]

Originally Posted by Gen13 F36

If your in UK ... you probably have to do the opposite

He would if it was an older Jag, etc.

[f30jay]

Originally Posted by Billfitz

Everything I've seen says negative. The logical reason for that is if you put a wrench or driver on the positive terminal and touch it to the chassis with the negative in place you'll get a very unpleasant result. As for the car settings, anything stored in iDrive memory isn't affected by disconnecting the battery, as the memory is non-volatile. You may have to reset the clock, but even that will reset itself if you have nav. The main reason to disconnect the battery is if you unplug some items, the seat belts or air bags for instance, while the battery is connected that can cause fault codes to be thrown, and the only way to clear them is with an OBD diagnostic and repair tool.

If you short out to ground the postive terminal it will still spark with the neg disconnected

[Billfitz]

If the neg is disconnected the chassis is no longer at ground potential, so there can be no spark.

[Gen13 F36]

Originally Posted by Billfitz

He would if it was an older Jag, etc.

I'm more like an Austin Healey kind of guy....

[ronanz]

Originally Posted by Gen13 F36

If your in UK ... you probably have to do the opposite

HA!! I see what you did there....🍻

.

[HarryTee]

Originally Posted by ronanz

HA!! I see what you did there....🍻

.

Hey, I'm intrigued! Why do people in the UK have to do the opposite?
And what did you see Gen13 did??

[Gen13 F36]

Originally Posted by HarryTee

Hey, I'm intrigued! Why do people in the UK have to do the opposite?
And what did you see Gen13 did??

UK built cars use to have positive ground system.... they probably don't do it now.

Example are old Jaguar and Austin Healey( when I mean old... i mean classic old)

Enjoy

[ArmyNurseRN]

To reset your electronics, you disconnect the source of energy, which is the anode, or negative terminal. Once you disconnect the negative terminal, you can apply a load to the system, such as putting on your 4 ways or pumping brakes to discharge remaining electrons from the system.

Disconnecting the positive terminal will only create a potential for arcing with the chassis ground or positive wire, since they are still being supplied energy from the anode.

Hope this helps.