leds turn on when ignition goes off?

Printed From: the12volt.com
Forum Name: Lights, Neon, LEDs, HIDs
Forum Discription: Under Car Lighting, Strobe Lights, Fog Lights, Headlights, HIDs, DRL, Tail Lights, Brake Lights, Dashboard Lights, WigWag, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=102209
Printed Date: May 15, 2025 at 7:43 PM

Topic: leds turn on when ignition goes off?

Posted By: sandantos
Subject: leds turn on when ignition goes off?
Date Posted: February 14, 2008 at 8:25 PM

I was hoping to get my door handle leds to turn on when my car turns off. I've read through a few posts, they basiclly say:

Connect one side to constant (cigarette lighter), and the other to a switched power source . My questions are:

1- So do i splice the + wire of my cigarette lighter and connect it to the + end of the led?

2-Are switched power sources anything that only turns on when the car is on (sunroof, etc.)?

If so, what do I connect the - end of the led to? The positive of the sunroof, or the negative? Any help would be much appreciated, crude diagrams are not only welcome, but encouraged.Thanks a bunch.

:oops:

Replies:

Posted By: ice32
Date Posted: February 15, 2008 at 8:51 AM

Here is the relay wiring only. you still need the required resistance for the leds your using, put them in after the relay on pin 30.

remember that if you use a 12v straight from the battery and wire up your relay like above, it WILL DRAIN YOUR BATTERY if you leave your car off for a long period of time. e.g over night or shorter depending on the draw of the leds.

you might want to rethink or add your thoughts to your post now that you no that. e.g when do you want them to turn off after that car is off?

p.s the middle pin of that relay is 87a if you can't read it in the image.

Posted By: Big Dog
Date Posted: February 15, 2008 at 11:21 AM

Assuming you have 12 volt LEDs:

Connect the anode to B+ (if it has presoldered wires then this is usually red).

Connect the cathode to ignition (if it has presoldered wired this is usually black).

No relays required.

No diodes required . . . this is what a LED is.

The instant ignition is turned off, the LED lights up.

Keep booster cables in the trunk....you'll need them if you don't start your car for a few days. posted_image

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Prepare your future. It wasn't the lack of stones that killed the stone age.

Posted By: Chris Luongo
Date Posted: February 27, 2008 at 9:09 AM

Does your car have a feature from the factory that turns on the domelight when you shut the car off? If so, you could just wire the LEDs in with the domelight.