I need a "Constant on when ignition is off" wire on top of dash. - Jeep Wrangler Forum
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Old 02-11-2014, 11:54 AM
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I need a "Constant on when ignition is off" wire on top of dash.

Is there a "constant on when the ignition is off" wire and a "power on when the ignition is on" in the 2010 JK's dash near the top of the dash above the gauges? I am installing a simple fake alarm LED and would like to find a wire close by the spot I am mounting it.

Btw... I found the perfect spot too. The little square removable plug on the top of the dash. I didnt want to drill a hole in my dash, so the little plastic plug is perfect for it.

Example pic...

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Old 02-11-2014, 05:16 PM   #2
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No, there is no "hot when off" wire to tap. But it's not hard to make something work like that.

You need a special kind of relay to do it.

Most relays (i.e. everything you find at the local parts store) is a "normally open" relay. So if you hook up the trigger to a "hot when ignition is on" source, it will supply power when you turn the key on. When you turn the key off, the relay cuts power.

What you want to find instead is a "normally closed" relay. They're hard to find since most people don't use them. This kind of relay works the opposite way that a regular parts store relay works. Hook up the trigger to the ignition and you'll get what you want. Turn the key on and the relay cuts power. Turn the key off and the relay supplies power. From there you run your wire to the LED you want.

I was doing some wiring of a fan controller and I needed a normally closed relay for a couple of things. The easiest I could find was one of these: http://www.summitracing.com/parts/pco-5591pt

It does both normally open and normally closed. Essentially, it takes the supply voltage and switches between two output terminals. But you could buy this one and just cap the normally open terminal, just using the normally closed terminal for what you want.


That being said, why do you want to have a fake alarm LED? Real alarms don't stop thieves. Fake ones would probably be even less useful. Just my $0.02.

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Old 02-11-2014, 05:22 PM   #3
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The accessories socket with a pic of a battery on the cover to the right of the climate control is always hot. You can tap into that hot lead but it will blink all the time. Or as derf recommended, use a relay designed to close when off. <--- This will most likely need to be connected to both the accessories and lighter socket for a constant feed and to let the relay know when ignition is off.
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Old 02-11-2014, 05:24 PM   #4
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The accessories socket with a pic of a battery on the cover to the right of the climate control is always hot. You can tap into that hot lead.
Awww yeah...... TAP that hot lead baby!
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Old 02-11-2014, 05:42 PM   #5
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Awww yeah...... TAP that hot lead baby!
LOL!!, i was even careful typing that in..... But I have a couple in me already.
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Old 02-11-2014, 05:55 PM   #6
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LOL!!, i was even careful typing that in..... But I have a couple in me already.
How many do you usually take at once?

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Old 02-11-2014, 05:59 PM
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Originally Posted by derf View Post
No, there is no "hot when off" wire to tap. But it's not hard to make something work like that.

You need a special kind of relay to do it.

Most relays (i.e. everything you find at the local parts store) is a "normally open" relay. So if you hook up the trigger to a "hot when ignition is on" source, it will supply power when you turn the key on. When you turn the key off, the relay cuts power.

What you want to find instead is a "normally closed" relay. They're hard to find since most people don't use them. This kind of relay works the opposite way that a regular parts store relay works. Hook up the trigger to the ignition and you'll get what you want. Turn the key on and the relay cuts power. Turn the key off and the relay supplies power. From there you run your wire to the LED you want.

I was doing some wiring of a fan controller and I needed a normally closed relay for a couple of things. The easiest I could find was one of these: http://www.summitracing.com/parts/pco-5591pt

It does both normally open and normally closed. Essentially, it takes the supply voltage and switches between two output terminals. But you could buy this one and just cap the normally open terminal, just using the normally closed terminal for what you want.


That being said, why do you want to have a fake alarm LED? Real alarms don't stop thieves. Fake ones would probably be even less useful. Just my $0.02.
sounds overly complicated. Wouldnt this work?how to install a dummy or fake flashing LED alarm in your car - YouTube
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Old 02-11-2014, 08:19 PM   #8
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The fused 12V wire going to the radio is always hot, and is right there. There's a bunch of always-on 12V wires near there, but radio is probably the easiest to deal with.

Go check out Mopar Connection Repair Kit to get an idea of what connectors in the vicinity have hot 12V circuits.
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Old 02-20-2014, 05:06 AM
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Thought I'd post a solution just in case anyone does a search looking how to do it.

Turns out it was MUCH EASIER than what others suggested. Not being very capable when it comes to automotive wiring it took me quite a few hours of experimenting and internet searching to figure it out. Hopefully by posting this I can save others from what i had to go through.

Anyway.... it turns out it was pretty easy.

The LED I got was a blinking one I got off of ebay for a few bucks. It came in a metal bezel (plastic bezel also available) in all kinds of different colors (I bought the blue). It had a resistor wired into it. It had two wires (red & black).

I found this pic on the net that shows what is what in the fuse box.

https://i.imgur.com/JenjyOD.jpg

I connected the red wire to the yellow circled empty fuse spot (the left red arrow in the pic). The black wire I put in the green-circled fuse spot (occupied by a fuse) indicated by the red arrow on the right.

The LED now flashes when i turn off the ignition and turns off when I start my jeep. I wish there was a way to have it work on a timer or when I lock my 2010 jk with the remote, but I guess ya can't have everything.
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Old 02-20-2014, 06:26 AM   #10
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Can't it be wired directly to the battery, using an inline fuse?
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Old 02-20-2014, 08:25 AM   #11
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Can't it be wired directly to the battery, using an inline fuse?
That'd be always on - he wanted a hot-when-off.

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The black wire I put in the green-circled fuse spot (occupied by a fuse) indicated by the red arrow on the right.
I'm not sure how I feel about it being grounded back into the fuse box in a different circuit - should probably be grounded directly to the body.
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Old 02-20-2014, 08:30 AM   #12
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That'd be always on - he wanted a hot-when-off.



I'm not sure how I feel about it being grounded back into the fuse box in a different circuit - should probably be grounded directly to the body.
You're right. He could also hook up a switch to it under the dash. I was thinking simple and easy and not messing with the electrical system at all. I totally missed the always hot part though.
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Old 02-20-2014, 01:10 PM
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That'd be always on - he wanted a hot-when-off.



I'm not sure how I feel about it being grounded back into the fuse box in a different circuit - should probably be grounded directly to the body.
I have not had any problems so far. No lightning bolt idiot light on the dash etc etc.. I have read several instructions/videos on the net that recommend it installed in this manner. I think it is called a "floating ground"
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Old 02-22-2014, 02:55 AM   #14
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Just don't trip CANbus or you'll have some odd things show up..

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