Hello-
I have a switch that fits in a blank in my Toyota dashboard that I'd like to use to light an LED light bar for my truck. The switch is a momentary switch (I believe) and has the following 6 pin outs (Switch Voltage +, Switch Voltage -, Switch Illumination +, Switch Illumination -, Switch Indicator +, Switch Indicator -). I hooked up my multimeter ends to the Switch Voltage + and Switch Voltage - pins and it only beeped for continuation when I was holding the switch. I would like to use this switch to turn on and off a 11.3A, 13.8V light bar at the front of the truck. I've read about 555 timers, flip flop relays, latching relays, but I'm honestly just confused. I'm a civil engineer and this just isn't something I have any experience with, but having a logical mindset, I can usually figure things out. Ideally I'd like to buy something that I could just wire in/out of between the switch, light, and battery, not against making something, but that's probably out of my skill set. The switch is internally lit when the headlights are on and I could tap power from a neighboring switch for that. The switch also has an indicator light that comes on when the light is on that I'd like to have operational as well. I tried to illustrate on the attached PDF, but I may be way off. Any help is certainly appreciated and I'll follow up with my results.

Thanks,
Brian

 

Welcome to AAC.

Based on your drawing, I've redrawn it in a more conventional way making it easier to be understood. Two questions I have are:
1) Are you certain this is a momentary switch? Or is it a latching switch? Meaning you push the button once to turn the LED's on or do the LED's only come on while you're holding the button?
2) You labeled your drawing with pins 7 through 12. Are there six other pins? If so - what function do they do?

 

I'm pretty positive that it's a momentary switch. I connected the probes of my multimeter to pins 8 and 10 to check for continuity. As long as I held in on the button of the switch, I got a tone. If I released the button, I lost the tone.

There are only 6 pins on the switch (see attached photo of back of switch). Sorry for the numbering confusion, I found the wiring diagram from a Toyota manual for this and the pins were labeled 7-12.

Thank you for re-drawing it properly, I think that I follow it, but what is the device at the top right? It appears to be some sort of relay possibly? It doesn't look like the typical relay that I've seen, but I'm a level 1 novice with this.

Thanks,
Brian

 

Your picture is the plug on the vehicle, not the switch. The switch itself may be numbered similarly, it doesn't matter. I was just wondering if there were other pins.

You're using an existing switch from Toyota? if you get tone only when pressed then yes, it's a momentary switch and isn't well suited for your purpose. I'll look at it further and I'm sure there's a way to use the relay to self-latch. The only problem with that is you'll need another switch to deactivate it - or shut the vehicle off. Even then there's no guarantee it'll shut off.

Yes, that's one older common method for drawing a relay. There are many conventions. Given my age I tend to stick with what I learned decades ago.

 

There's also a possibility what you're attempting to use is the CAN Bus. It may not be suitable for controlling after-market lighting. You may be better off just using the wiring harness that came with the lamp (assuming it came with one).

 

Suggest this 12 volt latching relay module that can be activated and deactivated with said momentary switch.
Only rated for 10 amps but use this module to control a 12 volt high current auto relay.
Available on Amazon.
NOYITO 1-Channel Self-Locking Relay Module One Button Start-Stop Bistable 10A Load for SCM Control, Household Appliances Control, Industrial Equipment Control (12V)

 

The switch pins shown in post #3 clearly aren't intended to carry much current. My guess is, as Tony said, they are for use with the CAN bus. They're fine for logic signals, but may not be able to carry the coil current drawn by a chunky relay capable of switching the 11.3A DC required by your light bar.
The module in post #6 is rated for only 10A. The chance of the contacts switching 11.3A reliably is likely to be low.
Can your light bar be operated with a switch in its earth/chassis connection, or is the casing of the light bar automatically earthed to chassis by its mounting arrangement?

 

Correct, the switch (see additional pic for more angles) is intended to send a signal back to the ECU which then sends a signal to the LED. My trim line of the vehicle didn't have this feature, so I'm hoping to bypass the ECU and use this low current switch to operate a relay to then switch on/off the light. The light bar has a wiring harness with 2 wires and is not automatically earthed by the chassis via its mounting. I have to run one of the wires to the chassis to ground it.

 

Since you prefer an off-the-shelf solution, a latching solid-state relay might suit your project, since it could be controlled by low current switches. I haven't looked into what makes/models are available.

 

Thanks, I suppose it doesn't have to be off the shelf, but it has to be something simple enough for this idiot to make!

 

Where are you located? That info would help find a supplier for your project.

 

I'm located in Kansas in the U.S. (Kansas City area).

 

IMHO, I think the idea presented in post #6 is the best one. You can use the module to operate this relay (which is rated for 15A), which then can switch the light bar on/off with successive presses of the pushbutton. Everything is wired as in this diagram:

 

Thank you. What is the NC (Normally Closed) connected to from the module?

 

I would get a standard 12 volt auto relay as mentioned in post 6. They are easier to wire and some include a wiring harness.

 

Thank you. What is the NC (Normally Closed) connected to from the module?

Nothing, not connected

 

Based on your sketch, would the attached be correct? Do you happen to know if there are standard housings for this type of module? Seems like something I wouldn't want exposed.

Thanks again, you've been very helpful.

 

I’m not familiar with auto relay pin numbering, but I think that the wire going to pin 87 should go to pin 87a.

UPDATE: @blavery if you wire the lights to pin 87, they would default to on. Then, depending where you get the 12V from, they would be on all the time. Plus, you would be drawing current from your battery whenever you had the lights off. I don’t think you want this.

 

Thanks, I'll review. I believe 87a is only on a 5 pin relay and I'd only need the 4 pin relay, but I can verify that.

 

Thanks, I'll review. I believe 87a is only on a 5 pin relay and I'd only need the 4 pin relay, but I can verify that.

You’d need the 5 pin relay unless you don’t care if you’d be drawing extra current to keep the lights off.