courtesy lights

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=121224
Printed Date: May 21, 2024 at 7:19 AM

Topic: courtesy lights

Posted By: micrors4racer
Subject: courtesy lights
Date Posted: April 08, 2010 at 12:00 PM

I am trying to put in footwell lights in a 1985 Toyota Corolla GT-S. Some how I can't find a +12v when the doors are open. Where can I find the +12v that turns on the dome light? The doors are negative trigger so it is 0 when the doors are open.

Replies:

Posted By: 91stt
Date Posted: April 08, 2010 at 3:37 PM

Depending on how much current the lightbar pulls, it may be better to +12V from the fuse box or better yet run a dedicated fused wire from the battery
Than you can use the door trigger for your switched ground

Posted By: micrors4racer
Date Posted: April 08, 2010 at 11:30 PM

So hook up a relay and use the ground as the switch?

Posted By: oldspark
Date Posted: April 09, 2010 at 4:53 AM

If it's low power (under a few Amps) and it is a normal earthing switch (with no sensing or other circuitry between your added lights & the switch), you should not need a relay.

Posted By: micrors4racer
Date Posted: April 09, 2010 at 2:22 PM

So postive from the leds to a constant 12v then the ground into the door switch? Wouldn't it short once I close the doors because it will apply both 12v from the positive then 12v from the door switch?

Posted By: oldspark
Date Posted: April 09, 2010 at 3:25 PM

What short? That's 12V to 12V.

And it's not a short - the LEDs are in between.

Posted By: micrors4racer
Date Posted: April 09, 2010 at 5:32 PM

Oh yea, wasn't thinking. I got them wired up now like that thanks!

Posted By: oldspark
Date Posted: April 10, 2010 at 12:53 AM

You weren't thinking? At least you have an understandable excuse.
I do think and I still make similar silly's!

What's worse is that I've worked for telco's that typically use +ve ground for traditional equipment so you'd think I'd be used to "inverted" drawing switching.
Yet I still have to think carefully about your situation. (Even though I have oft decribed the benefits of ground switching as used in most digital logic etc - aka Open Collector outputs.)

But these simple things are like a genius tying shoelaces - too trival to learn, or in out case, to waste our genii on.

Cheers.