LEDs in headlights

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=79281
Printed Date: May 08, 2024 at 3:19 PM

Topic: LEDs in headlights

Posted By: midnite_blue
Subject: LEDs in headlights
Date Posted: June 18, 2006 at 2:11 PM

i've been working on a mod involving using LEDs in my headlights... i've seen this done a couple of times before...

here's the deal- i used a Scanner LED (wires up so that it activates when ignition is shut off) then i put the LEDs in my headlamps and ran the wires... everything is being run to the interior fuse box. i tried splicing the LED source wires into the scanner unit. however, this causes the scanner not to work, and the leds only work at about half the brightness they should. i tried running another ground which powers everything, but being wired to the radio fuse, it keeps blowing it. on top of that, the radio will stay on after i remove the key (unless the face is removed) the radio amp is a 20amp fuse, the leds came from wal-mart ( the tag inside of the package says the leds use 0.04 amps.

my objective is for the leds in my headlamps to come on when the car is turned off and vice versa, the scanner is not important, i just thought that by splicing the leds into it, that they (leds) would work the same way as the scanner (also, not trying to make them flash or anything)

its a 2004 dodge neon / SX 2.0

any help is appreciated

Replies:

Posted By: midnite_blue
Date Posted: June 18, 2006 at 2:27 PM

actually, a more simple question would be:

how can i (safely) wire leds to come on when the car is shut off, but turn off when the car is started?

the current setup i have right now (without the scanner) is power being run to my keyless fuse, and a ground under a screww in the fuse box... with butt connectors spiltting the ground wire so that the leds light when connected, and go off when separated... but like the above question asks: is there any (hopefully simple) way for the leds to come off automatically when the car is started?

Posted By: scauntay
Date Posted: June 20, 2006 at 10:01 PM

the most simple way i could think of is run the leds to a constant 12v source and ground it then hook up a switch so you can just turn them off and on with or without the car on.

Posted By: midnite_blue
Date Posted: June 20, 2006 at 10:43 PM

scauntay wrote:

the most simple way i could think of is run the leds to a constant 12v source and ground it then hook up a switch so you can just turn them off and on with or without the car on.

thats actually what i ended up doing... however, i did find a way to get them to come on when the car is turned off... its not hard, but this method suits me better (ie. parking in certain places u don't wanna draw attn to yourself)

Posted By: compudude86
Date Posted: July 11, 2006 at 2:45 PM

try wiring them into your wiper circuit, its on in accessory and run, but off the rest of the time, i run my led lights off them, they draw very little, just put a 3amp fuse in between because a short with the leds will almost never blow the wiper fuse but will toast your led wiring, this comes from one who knows about replacing his lighting wiring once already. its a gm, so your circuitry may vary. also, on my gm, the fuse panel has a lead thats only hot in run, but once again, you MUST FUSE!! hope that helps

Posted By: kardain
Date Posted: July 22, 2006 at 2:43 AM

Use a relay.

I also own a GM, so I am familiar with which wires are 12v switched and 12v constant.

You will need a 5 pin relay.

Find a 12v switched and use that for the trigger wire. When the car is on, the relay is energized, it will flip to pin 87, which you don't want to hook anything up to. Lights turn off.

Pin 87a will be energized when the car is off, as it is the normally closed circuit. This is the pin that you want to hook the lights up to. Wire the rest of the relay as normal, and enjoy.

https://www.the12volt.com/relays/relays.asp

Posted By: keep_hope_alive
Date Posted: August 10, 2006 at 11:40 PM

i did something similiar with a custom time delay circuit for the LED "Halo" rings in my aftermarket headlights. Turns the LED's on with a flash from my parking lights when I arm/disarm my car - stay on for 3:15 minutes. Time delay is adjustable by changing the capacitor value. i decided on a delayed circuit so that i wasn't causing a drain on my battery for hours and hours. i just wanted the effect.

Here is the schematic, the final version had one 16V 10mF cap as opposed to the two 4700uF 35V caps pictured on the breadboard. Basically I use the 12 volt step input (parking light flash) to charge a large cap which provides enough base current into the NPN transistor to keep it on as a switch. This allows current through the relay coil which closes a normally open contact and completes the circuit turn on the LED Halos. Total current draw of 180mA. in short; the cap stores energy to keep the lights on when the car is off. the only limit on current is in the size relay you get. the transistor just serves the coil.
posted_image

then you could easily use another relay's normally closed contact to provide power to the circuit when the ignition is off and feed the circuit above from the battery.

that circuit was the analog version. the digital version is built and ready to be tested. it has an adjustable delay and uses logic instead of a simple cap feeding a transistor base.

although it's not exactly what you are asking, it is an alternative. the cool part is that i can arm my car by just locking my doors and the parking lights dong flash, so they don't turn on the LED's. that way i have the ability to not "stand out" if needed.

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