Wiring LED footwells in car, not as easy as you'd think

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  #1  
Old 09-17-12, 03:21 PM
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Wiring LED footwells in car, not as easy as you'd think

Hey everyone. I've ordered some LEDs to install in my car. Quite excited to install them!

I want them to power when I open my door (function the same as my dome light) and I also want to have a switch with which I can power them.

For now, I can just not worry about the switch though, I just need help with the wiring.

My car, (2010 Corolla) has a dome light, with two wires we need to worry about. We have a pink wire which is always live. Then, we have the gray wire, which is the switch on the circuit. It is live, until the door is open, where it is grounded. So its a negative switch.

I want to hook these up to my dimmer in my dashboard which is a positive circuit.

So, I am going to use a relay.

Would the correct configuration be:

(Confused a smidge about the order of 85 and 86 as a result of the negative switch, so is this right or do I have to flip or ground one?)(Or does the gray wire go on 85 and a different 12v on 86?)
85-pink wire
86-gray wire
87a- Dimmer
87- (could this just be any positive 12v source? or should it be related to the dome)
30- LEDs

Advice?
 
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  #2  
Old 09-18-12, 10:32 AM
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85 and 86 are fine. You can swap them and will work the same way. Nothing should be hooked to 87a. If Dimmer is a positive source then it can go to 87. 30 to the LEDs positive input and then you need a ground for the LEDs as well.

Or skip the relay as it is really not helping much. Dimmer to LED positive and grey to LED negative.

Either way should first check to see the current draw of the LEDs. The Dimmer feed might not be strong enough for a long string of LEDs.

Assume 12V relay and 12V automotive LEDs.
 
  #3  
Old 09-18-12, 02:09 PM
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I apologize for not making it more clear.

I want to have these lights be operated by the door opening, and have the ability to have them on when the dash is lit. So its two different sources.

I have been told the dimmer can handle it.

Knowing that I want both sources would that be right though?
 
  #4  
Old 09-18-12, 04:57 PM
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Yes, you should be fine and you have an efficient way to do it. I was wrong thinking the relay was for isolating for larger power draws.

Take the pink to 87 to do what you want. A separate 12v feed doesn't give you anything unless you want to throw a fuse on it.

For the switch get a SPDT - common to the LED positive, one leg to 30 and one to pink. That would be the on-all-of-the-time option.
 
  #5  
Old 09-18-12, 05:42 PM
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So you're saying have the pink go to 85 (or 86, it doesn't matter right?) as well as 87? I had wondered if I could do that. To do that, can I just strip a section of the pink and connect it with wire to both pins, having them originate from the same spot on the wire?

Also, just to be sure, I wouldn't need fuses on here, as all of this is coming from fused sources already? And finally, there is no need to worry about heat in the relay with 87 and 87a always having power to them, right (at least while the car is on)?

EDIT: Set up this way, where should I ground the LEDs?
 

Last edited by bazingax3; 09-18-12 at 06:07 PM.
  #6  
Old 09-18-12, 08:59 PM
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Anywhere along the length of wire is fine as this is all low current.
Make sure everything is solid so the wires can't touch accidentally.
Extra fuse is good so your dash lights don't go out if something goes wrong.
No heat issues when relay is not energized (no voltage across 85/86). Most relays generate under 1/2 watt when energized so not really any issue there either.

Ground can go to any bolt into the car body.
 
  #7  
Old 09-19-12, 10:50 AM
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So where should I put (a) fuse(s)? Only on 87a? Or on any that have to do with the light?

Do I not need to worry about heat build up on 87 or 87a? As they would be hooked up to a regular power source.

Finally, I believe the pink wire may always have electricity running to it, but since the gray one isn't grounded it won't release heat right?

I appreciate all the help!
 
  #8  
Old 09-20-12, 04:08 PM
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Bump!

[25 characters is a lot]
 
  #9  
Old 09-21-12, 11:26 AM
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Anyone? My lights ought to be waiting for me at home and I'm eager to install them!
 
  #10  
Old 09-23-12, 08:53 AM
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Ok guys,

right now I have my cigarette lighter and the grey wire hooked up to 85 and 86, and it sounds like its creaking when the doors open. So, I'm guessing it BARELY has enough power. I want to get rid of the sound.

I am going to hook up the pink and grey wires later to 85 and 86, but will that be able to handle a 40 amp relay?

Should I look into a mini relay or something?

I want to power about 62 leds with this so I don't know what I need. The box also does say what exactly sort of power consumption they have, so I don't know.
 
  #11  
Old 09-24-12, 11:30 AM
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Can you all look at this guide, and see, is the way the diode is used here ok?

DIY: Illuminated Footwells & Cupholders with Switch! - Toyota Nation Forum : Toyota Car and Truck Forums

Is a relay uneeded?
 
  #12  
Old 09-25-12, 08:15 PM
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Creaking noise might be caused by auto dimming lights as how they dim is to rapidly turn lights on and off. To verify connect the relay by itself.

Usually safe to draw up to 2 amps from pink, grey, and dimmer connections as I've seen Honda OEM LED kits that come with a 2 amp fuse.
62 LEDs in strips might be OK without relay. Individual would not. Can you get a multimeter with an amperage scale and measure when LEDs hooked directly to battery?

Diode in that link is there so that when the switch is on the dome lights don't come on too. Make sure diode is rated at least the current (amps) that the LEDs will use.
 
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