illuminated switch giving me some trouble
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Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=108217
Printed Date: May 10, 2025 at 2:15 AM
Topic: illuminated switch giving me some trouble
Posted By: y2j514
Subject: illuminated switch giving me some trouble
Date Posted: October 17, 2008 at 5:40 PM
So I am wiring up a switch to manually turn on my cooling fan and this is what I have done (taken from j-body.org). The only difference is, instead of a simple switch I am using an illuminated switch, that way I have a reminder that I left them on if I forget. My illuminated switch has 3 poles on it instead of 2 - obviously. 1: Power 2: Load 3: Ground. Now....if you look at the diagram 85 is basically a 12 v. When I connect both 1 and 2 to it, and then ground 3 only the light illuminates but no fan spinning. Do I have to run a separate 12v wire to the 1? 
Replies:
Posted By: i am an idiot
Date Posted: October 17, 2008 at 6:49 PM
Do you know if the light in the switch is an LED or a standard incandescent bulb? The way the switch is laid out is, the lamp is connected between the ground terminal and the load terminal. If it is a bulb you will have to apply constant 12v to the terminal that is labeled ground. Then ground the supply terminal and connect the load terminal to the relay. If it is an LED this will not work. Let me know if it is an LED device, we will have to modify your diagram a little bit.
Posted By: y2j514
Date Posted: October 17, 2008 at 9:35 PM
I'm not 100% sure...what is the most common type of illuminated switch out there? I would think its an led, but I could be wrong. I don't think it mentions anything about that on the box.
Posted By: i am an idiot
Date Posted: October 17, 2008 at 10:18 PM
Remove the switch from the vehicle, put a couple wires on the switch. One wire to the ground terminal, the other wire to the power terminal, connect the wire of the ground terminal to the positive terminal of the battery, briefly touch the wire on the power terminal to the ground terminal of the battery. If it does not light up, flip the switch and try it again. If it lights up you have a regular old bulb, if it does not light up it is an LED.
Posted By: y2j514
Date Posted: October 17, 2008 at 11:25 PM
This is the switch I have: https://shop2.aol.ca/shop/product--catId_1001983__locale_en__productId_388537.html From your last explanation - I think it is an old bulb, but I would actually have to go test it out to see. I'm tempted to go try now - but I really should wait for morning - its midnight here. Thanks for your help.
Posted By: y2j514
Date Posted: October 18, 2008 at 12:01 AM
assuming its a bulb which one of these, if any, is the correct way? I just don't understand why I can't use the same constant 12V for the load and the power.... 
Posted By: i am an idiot
Date Posted: October 18, 2008 at 12:37 AM
If that is your switch, that is an LED. You will have to ground terminal 85 of the relay. Then you will have to insert the switch between the power source and terminal 86 of the relay. Power to the power terminal of the switch, 86 to the load terminal. Ground the ground terminal of the switch.
12V DC 25A 3-position SPST on/off automotive red LED rocker switch
Detail Image
Price: $5.99
Posted By: y2j514
Date Posted: October 18, 2008 at 6:49 PM
Hey thanks I did get it to work finally by doing what you said. However, when I did your "test" to see if its incadesent or LED, when I put power across 1 and 3, I did get it to light up- so there is something wrong with your logic, or my switch was made differently. I ended up doing it like this:
I grounded 85
I cut 86 and put the end coming from the constant power to 1
then I took a wire from 2 to the 86 on the relay
then I grounded 3.
What I don't understand is why wouldnt, grounding 1, and then putting 85 on the switch, and then 12 V to 3 work? Its essentially the samething just backwards - an LED doesn't care which way the power is flowing through it
Posted By: spin2win
Date Posted: March 19, 2010 at 11:50 PM
Yes - LEDs are polar. Looks like the latest batch of Chinese switches can only supply +12v if you want the light to turn on when the switch is toggled.
Kind of sucks for those of us who want to switch a ground circuit.
Posted By: howie ll
Date Posted: March 20, 2010 at 3:37 AM
Doh the advert says LED switches.
Posted By: dualsport
Date Posted: March 24, 2010 at 9:03 PM
y2j514 wrote:
when I did your "test" to see if its incadesent or LED, when I put power across 1 and 3, I did get it to light up- so there is something wrong with your logic, or my switch was made differently.
The test as Iam described is accurate. The thing is, when you "put power across 1 and 3," it was to be applied in reverse polarity, with the +V connected to the ground. It shouldn't light up when you turn the switch on.
Did you maybe think "flip the switch" meant reverse the connections rather than "turn the switch on"?
To make it easier, if you simply connect power across the Ground and Load inputs of the switch, see if you get it to light up with the power connection both forward and backwards. If it lights up only one way, then it's as expected for LEDs. If you can get it to light up both ways, then you do have something special.
Posted By: dualsport
Date Posted: March 24, 2010 at 9:12 PM
y2j514 wrote:
My illuminated switch has 3 poles on it instead of 2 - obviously. 1: Power 2: Load 3: Ground.
Just for fun facts, those are usually referred to as terminals, not poles. The switch has only one pole, as in Single Pole Single Throw (SPST). The number of poles indicate how many individual signals or power lines the switch can transfer. In this case, one.
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