NOT dashcam related, but NEED HELP!

[romuhhhr]

So I have a european version stalk switch and I want to wire the rear fog to work independently. My issue is that the switch is spring loaded. When I turn the stalk switch to turn ON the rear fog, it automatically goes back to front fog position. Are there any relay of some sort that I can use in order to keep it ON or OFF when I need to?

 

[SawMaster]

Look up "latching relay". It's an electronic circuit/relay which will give you the action you want. Probably can be had as a kit or pre-assembled.

Phil

 

[romuhhhr]

Thank you @SawMaster. Will definitely look that up!

 

[romuhhhr]

@SawMaster

Do you think this will work?
KNACRO DC 12V 2-Channel Self-Latching Relay Module One-Button Bistable Switch One-Button Start/Stop High-Level Trigger

 

[SawMaster]

It looks like it would work, but you've got a lot of wiring to do- it's not going to be anywhere close to 'plug-and-play'. According to the relay's specs, one 'pulse' of current from the stalk switch will close the relay, then the next will open it. So going into the spring-loaded stalk switch position turns on and leaves on, as doing that agin turns off and leaves it off. There's a parasitic drain on the relay control circuit, so power for it will need to come from a switched 12V source. That will need to be fused.

Personally,l I'd just hack the existing wire and add a SPST switch somewhere for the rear light as a cheaper and easier solution to implement and to easier to reconnect when I sold the car. But that relay seems like it will give you the functionality you seek if it's wired up correctly so the choice is yours.

Phil

 

[romuhhhr]

@SawMaster

I found this also, and it looks like it's easier than the previous one I posted.

https://www.amazon.com/gp/B015MRQNXS

 

[SawMaster]

That one is rated 10A@24VDC so it would be about half that for 12VDC. 5A probably isn't enough current-carrying capacity for your light, but you could 'cascade' a better relay downstream. I do hope you know something about car wiring and electronics- this kind of project ain't for the average handyman type- as this will be complicated and I can't exactly talk you through it very well from a distance. Even though I could do the job it's like I said: I'd just put that light on a separate switch and live with it that way. Much less time and hassle going about it that way 😉

Phil

 

[EsQueue]

That one is rated 10A@24VDC so it would be about half that for 12VDC. 5A probably isn't enough current-carrying capacity for your light, but you could 'cascade' a better relay downstream. I do hope you know something about car wiring and electronics- this kind of project ain't for the average handyman type- as this will be complicated and I can't exactly talk you through it very well from a distance. Even though I could do the job it's like I said: I'd just put that light on a separate switch and live with it that way. Much less time and hassle going about it that way 😉

Phil

Probably a simple misunderstanding on your part but 10A@24VDC = 240 Watts which is their claimed rating. That means that it should be able to 20A@12VDC which equals 240 Watts. 12VDC@5A is only 60 Watts. I'd never push these devices to their max ratings but that should easily be able to handle fog lights according it it's claimed ratings.

As for his project, it should be simple granted that his car doesn't use CAN Bus to complicate things on the lights.

@SawMaster

I found this also, and it looks like it's easier than the previous one I posted.



View attachment 47467

From what I understand, his light switch is functioning almost as a momentary switch and reverts to off as soon as the switch is released. The above relay has a memory feature where it remembers your last input in the event of a power failure. The way I would achieve what you want would make that relay problematic. You want a relay that resets of off when power is lost. Here is a 12V switching relay for dirt cheap. It has low level (ground) and high level (12v) activation.

Find out if your lights signal has a switching ground or 12v source and set the relay accordingly. Power the relay using a power source that Shuts off when the car is off. Use the intermittent light signal to activate the relay latching it on. Turn it off by repeating the same action or turning the vehicle off. The relay has a red light on the board. If you are feeling adventurous, you can desolder the LED and run your own light behind the dash or somewhere else.