Wiring LEDs in car

Thread Starter

FJVDB

Joined Mar 13, 2020
6
Hello all,

I have a way I want my LEDs to work in my Toyota FJ cruiser and I need some advice on how to wire it to.

I want my LED strips in the footwells to turn on with switched power (ignition) when the doors open. So a relay signaled by the door circuit (or another solution). While also having a switch that I can toggle to turn the lights on when desired. I want to use a specific switch that is a SPST because I don't like funky looking switches. If anyone knows if this is possible with this switch then any help is appreciated.
 

dl324

Joined Mar 30, 2015
10,467
Welcome to AAC!
I want to use a specific switch that is a SPST because I don't like funky looking switches. If anyone knows if this is possible with this switch then any help is appreciated.
It's probably possible. Can't say for certain without more specifics.
 

shortbus

Joined Sep 30, 2009
7,597
The trigger for the door would be a hot wire.
Don't know about Toyota, but most cars the door switches are always hot, and ground when the door opens to turn on the light. They do this so they don't need two wire to the door switch. Have nothing at all to do with the ignition switch being on or not, if the ignition needs to be on, how would the interior lights come on when you first get in the car?
 

Thread Starter

FJVDB

Joined Mar 13, 2020
6
Don't know about Toyota, but most cars the door switches are always hot, and ground when the door opens to turn on the light. They do this so they don't need two wire to the door switch. Have nothing at all to do with the ignition switch being on or not, if the ignition needs to be on, how would the interior lights come on when you first get in the car?
All true, I'm no expert. So use the ground to trigger a relay?
 

shortbus

Joined Sep 30, 2009
7,597
You haven't given near enough information about what your working with. Why do you only want to limit to a SPST switch? most switches in most styles are available in other configurations. Why do you think your LED strip would need a relay? Does it draw more current than the filament bulbs used in the interior now?

All that said, it's possible that you would only wire the LEDs to the same fuse and circuit the interior lamps now use, running them in parallel to the existing circuit. But it's hard to tell with out being there to see what your doing.
 

Thread Starter

FJVDB

Joined Mar 13, 2020
6
You haven't given near enough information about what your working with. Why do you only want to limit to a SPST switch? most switches in most styles are available in other configurations. Why do you think your LED strip would need a relay? Does it draw more current than the filament bulbs used in the interior now?

All that said, it's possible that you would only wire the LEDs to the same fuse and circuit the interior lamps now use, running them in parallel to the existing circuit. But it's hard to tell with out being there to see what your doing.
I want to use an OEM style Toyota switch. The one I included an image of. It doesn't necessarily need a relay. I just want to be able to switch it on and off in the car, while it also turns on by the door.
 

Thread Starter

FJVDB

Joined Mar 13, 2020
6
So let's say I turn the switch off, the next time I get it the truck I still want it to turn on with the door open.
 

Tonyr1084

Joined Sep 24, 2015
4,361
Typical door light switch (minus a fuse): (battery; lamp; door switch)
1584211097163.png

With an LED meant for automotive use:
1584211239553.png

If you want to be able to turn it on all you need is to connect your switch from ground to the black wire on the LED. But that will also turn on the regular light. You might want to use a diode to isolate the ground when operating through a manual switch instead of the door switch.
 

Tonyr1084

Joined Sep 24, 2015
4,361
OR a SPDT switch (always get those mixed up but the drawing is correct) Forget the diode thing; not good advice:
1584211618208.png

Personally, I hate light when I'm driving at night. Dash lights are dimmed as much as is reasonably possible. Hate the bright face of the stereo. I like a dark interior when driving at night.
 

dl324

Joined Mar 30, 2015
10,467
Hate the bright face of the stereo.
I hear you. The information/GPS display in our 2013 Explorer is too bright at night. Wonder if anyone at Ford has heard about an automatic night mode (pet peeve of mine; the whole instrument cluster display is retarded). The GPS on my Samsung phone does it. My 20 year old BMW has a sensor and adjusts brightness based on ambient light level.
 

Tonyr1084

Joined Sep 24, 2015
4,361
My Chevy S10 pickup had it on the stereo. Turn the lights on (or automatic) and the face would dim. After market stereo's had that feature as well. Also, the S10 (2002) had a feature where the volume would go up with speed and down when you slowed or stopped. Wind and highway noise would be compensated automatically. Some nice features engineers have forgotten about.
 

dl324

Joined Mar 30, 2015
10,467
Also, the S10 (2002) had a feature where the volume would go up with speed and down when you slowed or stopped.
The Explorer has that, so does the 00 BMW. My Wife keeps saying I can't compare BMW features to an American car, but with the American car 13 years newer, so I think it's appropriate.
 

Thread Starter

FJVDB

Joined Mar 13, 2020
6
Typical door light switch (minus a fuse): (battery; lamp; door switch)
View attachment 201491

With an LED meant for automotive use:
View attachment 201492

If you want to be able to turn it on all you need is to connect your switch from ground to the black wire on the LED. But that will also turn on the regular light. You might want to use a diode to isolate the ground when operating through a manual switch instead of the door switch.
Another option in my case is to wire it on the dash lights dimmer, that way it would dim and brighten as the doors open/close. It's an 2008 FJ cruiser and it doesn't have the features mentioned. I may just wire up 2 sets of light up with one on a SPST switch and the other on the door circuit. In a newbie and that's all I can think of.
 

Tonyr1084

Joined Sep 24, 2015
4,361
Another option in my case is to wire it on the dash lights dimmer, that way it would dim and brighten as the doors open/close. It's an 2008 FJ cruiser and it doesn't have the features mentioned. I may just wire up 2 sets of light up with one on a SPST switch and the other on the door circuit. In a newbie and that's all I can think of.
That might not work as the door light switches are on a separate circuit. If you wire into the dash lights then when you open or close the door your LED's won't respond. You COULD build a dimmer for the LED's, but that's another thread for you.

I suppose it's possible to get power from the dimmed dash lights, but I believe they are powered in the same manor - battery - lights - dimmer control module - ground. I don't think the lights are controlled by dimming the positive feed, but rather the negative "sink" to ground is where the dimming occurs.
 

kaindub

Joined Oct 28, 2019
15
Hi FJVDB
I'm going to spoil the party
Modern vehicles use a canbus system to interface switches and lights (and other things) The switches and lights go to one of the body computers. The computer takes all the inputs and then decides what to turn of, turn off etc.
Its not a simple case of just tapping into the existing wiring
As an example. In the old days (pre body computers) if you wanted to make a trailer lighting outlet you just tapped into the rear light harness and wired it to a plug. With a modern body computer car, thats not possible (you get faults on the dash) and you need to use a special interface box provided by the car manufacturer.
By all means try the suggestions above, but do not be surprised if you get light warnings or it doesnt work as expected.
Not as simple as the old days
 

DarthVolta

Joined Jan 27, 2015
382
I want to buy a smoke machine to blast out a big puff of smoke when I stop and park my car.

Not like cheech and chong , I mean like the Back to the Future effect on the Delorean, or a spaceship landing in Star Wars
 
Hello all,

I have a way I want my LEDs to work in my Toyota FJ cruiser and I need some advice on how to wire it to.

I want my LED strips in the footwells to turn on with switched power (ignition) when the doors open. So a relay signaled by the door circuit (or another solution). While also having a switch that I can toggle to turn the lights on when desired. I want to use a specific switch that is a SPST because I don't like funky looking switches. If anyone knows if this is possible with this switch then any help is appreciated.
What we need to know is your exact plan - what do you want to achieve in terms of features and level of automation.

Prerequisites:
- You have a hot wire (12V) available to power the LEDs. This can be the existing outlet for door lights, or any other supply if you need to.
- You have a trigger signal to indicate the doors are open. This can be the negative ground for existing door lights.

Level of automation:
- Do you want them to turn on, regardless of the manual switch position?
- Do you want a permanent-on and/or permanent-off position?
- Do you want the LEDs to turn on separately from the existing interior lights? If so, only if manual, or also when the doors open?

You need to clarify what you want to achieve. If you manually turn them off, do you want them to turn on again the next time you open the door?
 

MisterBill2

Joined Jan 23, 2018
5,741
Hello all,

I have a way I want my LEDs to work in my Toyota FJ cruiser and I need some advice on how to wire it to.

I want my LED strips in the footwells to turn on with switched power (ignition) when the doors open. So a relay signaled by the door circuit (or another solution). While also having a switch that I can toggle to turn the lights on when desired. I want to use a specific switch that is a SPST because I don't like funky looking switches. If anyone knows if this is possible with this switch then any help is appreciated.
Certainly it is possible! But it may be a bit more complex than you would like. IT can certainly be done to use the switch that you choose, even if that switch is a very low power device. What can be achieved is limited by how much complexity you will accept. And sometimes cost may also enter the discussion.
The worst case option would include adding another switch for each door involved, which could then easily allow you to have only the associated LEDs switch on.
 

MisterBill2

Joined Jan 23, 2018
5,741
Hi FJVDB
I'm going to spoil the party
Modern vehicles use a canbus system to interface switches and lights (and other things) The switches and lights go to one of the body computers. The computer takes all the inputs and then decides what to turn of, turn off etc.
Its not a simple case of just tapping into the existing wiring
As an example. In the old days (pre body computers) if you wanted to make a trailer lighting outlet you just tapped into the rear light harness and wired it to a plug. With a modern body computer car, thats not possible (you get faults on the dash) and you need to use a special interface box provided by the car manufacturer.
By all means try the suggestions above, but do not be surprised if you get light warnings or it doesnt work as expected.
Not as simple as the old days
Certainly it is possible to add the functions described even in a car totally infected with the canbus system. But it would be a bit more work and complexity, and would not be attached to that computer system at all.
 
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