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Discussion Starter #1
I've been wanting to get a light bar for my mouth but haven't gotten too far because I haven't found a switch I like. I want something that looks like it belongs. There are switches that fit the OEM cutout, but the covers are oversized, don't match the rest of the switches and just look ridiculous. So I thought I'd look for an OEM switch that would work as a relay trigger. Finally found a wiring diagram idea for our roof lamp switch, courtesy of the fine folks at titantalk.com. It goes into a bit of the pin layout and the OP is looking to do the same thing as I mentioned. Thanks to 20titan12!


Now I just need to make up my mind on which lightbar to purchase.
 

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Discussion Starter #5
Thanks but that's what I'm trying to avoid because it'll be one switch that's different from the rest. If I were to need more, like yours, it would be fine because it wouldn't be the ugly duckling switch.

I just bought one of these:
125393


It'll go right next to the roof lamp button and be wired to the mouth LED bar.
 

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Discussion Starter #7
Still working on this. Thanks to Titantalk, I've decoded the pins on the back of the off road lamp switch. There are 6 pins running vertical that work in 3 pairs:

  • from 12V source (parking lights)
  • relay trigger signal
  • from dash lights so the button lights up when the lights are turned on
  • ground
  • from the "switched on" connection of the triggered relay (turns on the lamp on indicator light)
  • ground
Now I'm working on finding a latching relay that doesn't have to come from the UK because shipping is $25. I think I can make a latching relay by wiring together 4-5 standard Bosch relays. But who wants to do that? Anyone here really know relays?
 

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A relay is nothing more than an electronic switch. The difference is that it uses an electronic signal (12v DC in this case) to either turn on or off. NC refers to normally closed or “on” when there is no voltage while NO is normally open or “off” when there is no voltage.

So if you are using a relay with a switch wired to the NC terminal, the relay will turn off the device when you turn the switch “on”. To put it more technically, when you complete the circuit on the input side the relay will open the circuit on the output side. The opposite would be true if you wired it up to the NO terminal. In this case the relay would be doing exactly the same thing as the switch just isolating the higher amp circuit.

Relays should always be used to protect circuits as switches are not designed to handle high amp loads. The one exception I made to this on my rig was for my CB radio since it only draws 5 amps. There’s a good sticky about wiring at the top of this forum page (sorry link didn’t work).
 

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Discussion Starter #9
Thanks for the link, but it wouldn't open for me. So the issue I've run into is needing a latching relay or switch. The OEM button is a momentary switch, so when it's pressed, there is a 12V signal during the action but as soon as it's released, the signal stops, so a regular relay would go back to it's resting state, whether NO or NC. I need one that will take a pulse, move from NO to NC and stay that way until I press the button again and have it move from NC to NO. I think a solid state relay would be the best option, but finding the right one is where I'm stuck. Once I find it, the rest will be a breeze.

Here's the relay that will work, but finding it's US equivalent is tough. Doesn't have to have the same form factor, just be functionally identical.

 

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Thanks for the link, but it wouldn't open for me. So the issue I've run into is needing a latching relay or switch. The OEM button is a momentary switch, so when it's pressed, there is a 12V signal during the action but as soon as it's released, the signal stops, so a regular relay would go back to it's resting state, whether NO or NC. I need one that will take a pulse, move from NO to NC and stay that way until I press the button again and have it move from NC to NO. I think a solid state relay would be the best option, but finding the right one is where I'm stuck. Once I find it, the rest will be a breeze.

Here's the relay that will work, but finding it's US equivalent is tough. Doesn't have to have the same form factor, just be functionally identical.

Sorry about the link not working but it’s at the top of the forum page. The momentary aspect certainly complicated this. Based on some quick research even with a latching relay (aside from the one you found) you would need 2 different momentary signals. One to trigger and one to reset. I did however find this diagram that I believe will get you the result you need/want and a link to the page. Should be a fairly straight forward circuit to recreate. The black cylinders are 1-2 amp diodes that you can source online (or at an electronic hobby shop if one is near you, they’re becoming extinct though). By the time you piece the components together below it might be cheaper to pay the $25 for shipping since it looks like the relay you found will work.


https://www.the12volt.com/relays/relaydiagram23.html

 

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Discussion Starter #11
I found that post also. And the diagram below that image with the 5 relays to eliminate the diodes. I found a 5-pack of Bosch style relays for $25 on Amazon. Part of me just might go this route because those relays are cheap and wiring this up would be a cakewalk. I was just trying to avoid having to put a microwave sized contraption under my dash. Plus, counting the diodes, it's 6 more failure points.

Just think...A solid state latching 12V relay...No magnets to get tired, no moving parts, no mechanical failures and one piece. You'd think it would be more common than it is...
 

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Discussion Starter #12

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Looking good. Have you considered editing the thread title to something that will help people find this in the future? Could be useful info for others, and a title matching the nature of your project could make it easier to search for.
 

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Discussion Starter #18 (Edited)
Edit: Here's a cleaner version from the other site:

Here's a little project I'm working on. Most of it's done now that I have the wiring figured out. Not the prettiest job but it'll get cleaned up after I get the light bar mounted. I wanted to find a switch that would fit the blank next to the factory Off Road Lamps button. Couldn't find one that didn't look goofy. I wanted a stock appearance and the switches with curves and bumps and stuff just didn't sit right with me. So I did some research and the nice fellows at Titan Talk had completed something similar using our Off Road Lamps button. So I bought one. And then pooped myself trying to figure out what to do next.



The switch has 6 pins on the back and is a momentary switch; it doesn't latch...Just creates a short to activate the lights. To simplify, the 6 pins are actually 3 pairs - top 2 create the short to activate the lights, middle two are for the illumination and the last 2 are for the orange 'lights on' indicator LED.

Here are some pics of my process:




You can see my initial notes are incorrect. This one stumped me a little bit.


Inserted pins and then used 5-minute epoxy to secure them in place.


Testing...


Testing...


I dig the look...


Always keep your fuses close to the source!


Bosch relay fits perfectly in the relay box.


Here's what I used instead of a latching relay. The latching relay was $25, in the UK with a $25 shipping charge. Nope. This little gem does the same thing and is $16.





The grounds.


Strapped down.


My initial kit...The old latching relay thing is 5V, so I have a 12V to 5V converter. Bought the 12V version because I didn't want to have an additional failure point.

Here is what I wired up:


Now I just have to mount the LED bar in the mouth and run the power wire. Positive lead connects to the same lead of the relay that is connected to the Lamp On Indicator of the switch. Negative to ground. Then it's done!
 
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