Do i need to disconnect the battery...

[jamesters]

Hello need replace electric window switch....would i need to disconnect the battery or would the car being swiched off be enough to do it?

[Krikkit]

I wouldn't bother.

[xjay1337]

Only time I disconnect battery is for airbag related things nothing else.

[jamesters]

Yeah thanks 🙂

[jamesters]

Yeah thanks 🙂 guessing same for wing mirrors with built in indicators to

[littleredrooster]

In the very unlikely event that the windows work with the ignition off, then you would need to disconnect the battery just in case a live wire accidentally went to earth.

Remember that if you do want to disconnect the battery on anything vaguely modern, you need to wait for the various systems (ECU, BCU etc.) to go to sleep first. Killing the power before they're completely inactive can fry them.

[xjay1337]

littleredrooster said:

Remember that if you do want to disconnect the battery on anything vaguely modern, you need to wait for the various systems (ECU, BCU etc.) to go to sleep first. Killing the power before they're completely inactive can fry them.

Can you give some sources on that information , as I have never come across that working on any VAG or BMW car certainly.

So I'm interested in how removing a power source can "fry" something.

[Dogwatch]

According to Haines disconnecting the battery is the first step in doing almost *any* work on the car. Whole thing is so backside covering that the occasions where it really is good practice are swamped by those where the worst that can happen, if you are unlucky, is a blown fuse.

[Penelope Stopit]

As above, don't disconnect battery

Disconnect it cleanly, keep it in the off position

[littleredrooster]

xjay1337 said:

littleredrooster said:

Remember that if you do want to disconnect the battery on anything vaguely modern, you need to wait for the various systems (ECU, BCU etc.) to go to sleep first. Killing the power before they're completely inactive can fry them.

Can you give some sources on that information , as I have never come across that working on any VAG or BMW car certainly.

Not directly, just 50+ years of fixing the damn things, and more recently having a drink with my Auto-elec mate who - at one stage - was fixing 3 cars per week with non-functioning electronics caused exactly by this.

xjay1337 said:

So I'm interested in how removing a power source can "fry" something.

Fry was possibly the wrong word - 'Spiked' may be better as many people struggle to get a clean break when pulling the battery terminal off and end up with it sparking half-a-dozen times before it comes off.

[MRichards99]

No I wouldn't disconnect it for what you're planning to do