Looking For A Ground When Ignition Is Off?
Printed From: the12volt.com
Forum Name: Car Security and Convenience
Forum Discription: Car Alarms, Keyless Entries, Remote Starters, Immobilizer Bypasses, Sensors, Door Locks, Window Modules, Heated Mirrors, Heated Seats, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=147668
Printed Date: May 09, 2025 at 8:48 AM
Topic: Looking For A Ground When Ignition Is Off?
Posted By: dsincolorado
Subject: Looking For A Ground When Ignition Is Off?
Date Posted: May 14, 2023 at 6:11 PM
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
Replies:
Posted By: i am an idiot
Date Posted: May 14, 2023 at 7:14 PM
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.
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Let's Go Brandon Brown. Congratulations on your first Xfinity Series Win. LGBFJB
Posted By: davep.
Date Posted: May 18, 2023 at 12:39 PM
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+.
Posted By: dsincolorado
Date Posted: May 18, 2023 at 1:08 PM
Great tip, I'm going to poke around the ignition wires this weekend. I'll let you know!
Thanks, Dan
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