Yes, installing your own LEDs on your car, motorcycle or in your home is often said to be easy – but hey, if you need LED install help, it’s just as easy to ask.

Customizable LED strips can add a pretty awesome effect to anything. So, if you’re looking to add a LED strip and have it turn on with a dome light, there are several steps you need to go through first:

Determine if your dome light is positive or negatively switched

Which wire is disconnected when the light is off and vice versa

Establish the amperage draw of your LED strip

Calculate the proper fuse and diode to use

Once you’ve established these factors, there are two diagrams to use –

Diagram 1 
If your dome light is negatively switched: 
User posted image 

Diagram 2 
If your dome light is positively switched: 
User posted image

 


FORUM THREAD


bman11

Joined: Nov 23 2008
Posts: 12
Post Sun Nov 23, 2008 4:55 pm

OK, so i have decided to put led flex strips in my car. Here is my wiring diagram. The blue lines r the 9.5” flex led strip. Now i couldnt find how many amps each of those strips are, so my first question is, what size fuse would i need? my second question is, i wanna have these lites on a hand off auto so that i can just turn them on, but also have them come on with my dome light, could somebody please show me how to wire that in. (thats what the extra line coming off the switch is for.)

EDIT: i have electrical experience, just on industrial, and ac, not so much diodes and all that jazz.

EDIT: I found the amperage, so i guess a 1amp fuse would work for all of these. just need helpw iring to my dome lights.

Phil
Owner, Oznium.comJoined: Feb 11 2003
Posts: 7719
Post Sun Nov 23, 2008 6:23 pm

You’ve got the right idea. Please let me know if I can clarify anything below.

First, you need to figure out if the dome light is positively or negatively switched. This means, is the positive or negative wire always connected? Which wire is disconnected when the dome light is off? Which wire is connected when the dome light is on?

Most cars I’ve come across use a negatively switched setup. This would mean the negative/ground wire is connected and disconnected, and the positive wire is always connected.

Calculating the proper fuse
Once you’ve figured out the amperage draw of each LED strip from the technical info page, you can then calculate the appropriate fuse size. In your case, 6 x 9.5″ LED strips would draw just under 1 amp. The purpose of a fuse isn’t really to protect the LED strip, but rather protect your wiring in case of a short. In this case, you can use a 3 amp fuse and be just fine.

Calculating the proper diode
Diodes have an amperage rating, and you might as well get that is capable of handling anywhere from 2 to 5 amps.

Diagram 1
If your dome light is negatively switched:
User posted image

Diagram 2
If your dome light is positively switched:
User posted image

Tim

Joined: Nov 16 2003
Posts: 10795
Location: Kalamazoo, MI
Post Sun Nov 23, 2008 6:34 pm

Nice diagrams Phil. That’s what this place needs, a bunch of diagrams like that for various installations.
bman11

Joined: Nov 23 2008
Posts: 12
Post Sun Nov 23, 2008 11:12 pm

hey man, those pics r great, just wondering if u can clear one thing up for me. In my course i took, we just briefly went over diodes, and i just want to see if i get waht going on. the diode is just acting like a resistor and to limit the voltage?
Phil
Owner, Oznium.comJoined: Feb 11 2003
Posts: 7719
Post Mon Nov 24, 2008 12:06 am

The diode prevents current from running back into the dome light when you flip your on/off switch.

The diode is like a one-way valve. Current can flow from the dome light, but not back to it.

Check this out: https://www.the12volt.com/diodes/diodes.asp

bman11

Joined: Nov 23 2008
Posts: 12
Post Mon Nov 24, 2008 10:20 pm

cool, thanks for your help man, actually learned how it works instead of just being told what to do. biglaugh.gif