Looking For A Ground When Ignition Is Off?

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dsincolorado

Member - Posts: 2

Joined: May 14, 2023

Location: Colorado, United States

Posted: May 14, 2023 at 6:11 PM / IP Logged

Hi everyone, hoping you guys might be able to help a newbie. I’m trying to install a simple flashing LED but need it to be powered only when ignition is off. In my Xterra I’ve found plenty of hot wires, but so far cannot find a wire that is grounded ONLY when the ignition is off.

Any help would be sincerely appreciated.

Thanks, DS in Colorado

2005 Nissan Xterra

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i am an idiot

Platinum - Posts: 13,667

This member consistently provides reliable information

Joined: September 21, 2006

Location: Louisiana, United States

Posted: May 14, 2023 at 7:14 PM / IP Logged

Connect the positive LED wire to constant 12 v. Connect the negative LED wire to an ignition wire.

Or, use a relay. Ground to 85 and 30. Ignition to 86. 87A will be ground when ignition is off.

Let's Go Brandon Brown. Congratulations on your first Xfinity Series Win. LGBFJB

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davep.

Gold - Posts: 641

Joined: May 27, 2011

Location: California, United States

Posted: May 18, 2023 at 12:39 PM / IP Logged

IAAI, I took the liberty to make it a little clearer.

I've used this method numerous times, and it works, but there can be a catch. If you loose the power on the "HOT" side, the reverse current limit of the LED will be exceeded, and the LED will be destroyed. I now put a 1-amp diode in series with the LED in its forward direction to protect it against loss of B+.

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dsincolorado

Member - Posts: 2

Joined: May 14, 2023

Location: Colorado, United States

Posted: May 18, 2023 at 1:08 PM / IP Logged

Great tip, I'm going to poke around the ignition wires this weekend. I'll let you know!

Thanks, Dan

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