Foglights Auto On

[gabbygenier]

Foglights On With High Beams

 

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10/18 diode jump gets them on with high beams.

 

10/22 gets them on with parking lights

 

 

The information your looking for is in that thread. As stated above

 

 

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I did mine so they come on when low beams are on or DRL. It's here somewhere as a thread. I'll look for it.

 

So i just read through a lot of pages and there's one little detail that seems i would want that this mod does not offer.

 

i would like to still be able to control the fog lights with the stock switch.

 

 

 

Or we can just program your BCM to remember the last state of the switch ;)

 

Seems like this may be the only way to do what i want to do really.

[arcasey]

 

 

 

 

 

 

 

So i just read through a lot of pages and there's one little detail that seems i would want that this mod does not offer.

 

i would like to still be able to control the fog lights with the stock switch.

 

 

 

 

Seems like this may be the only way to do what i want to do really.

 

Actually, I think there may be a way for you to do what you want: fog lights auto on with headlights/DRL's and use the stock foglight switch to turn them off and then back on again. I haven't drawn it out yet but I think you can do this with a Latched ON/OFF with Momentary Pulse type circuit. This circuit would be similar to a push button start circuit. It just depends on how intricate you are willing get with the wiring because it would require quite a few relays to make the circuit work. I'll see if I can draw up the circuit and make sure it will work on paper. Here is a video of how the circuit works:

 

 

 

There is a link in the video's description that will carry you to a site showing exactly how to wire the circuit shown in the video. Once you have the circuit shown in the video the only thing to figure out is how you can use that 12V output to break the foglight circuit. I think this can be done with another 5 pin relay.

[gabbygenier]

 

Actually, I think there may be a way for you to do what you want: fog lights auto on with headlights/DRL's and use the stock foglight switch to turn them off and then back on again. I haven't drawn it out yet but I think you can do this with a Latched ON/OFF with Momentary Pulse type circuit. This circuit would be similar to a push button start circuit. It just depends on how intricate you are willing get with the wiring because it would require quite a few relays to make the circuit work. I'll see if I can draw up the circuit and make sure it will work on paper. Here is a video of how the circuit works:

 

 

 

There is a link in the video's description that will carry you to a site showing exactly how to wire the circuit shown in the video. Once you have the circuit shown in the video the only thing to figure out is how you can use that 12V output to break the foglight circuit. I think this can be done with another 5 pin relay.

That's a good idea that i never even though about. just figured there was maybe an easier way that someone already figured out.

 

only thing is it wouldn't need to be that complicated. We would only need one relay really if the fog light switch is a simple on/off switch. If it is and we assume its always a negative output until its turned on. we could just add a relay to swap the negative output to make it a positive output so it would always be on instead of off.

 

now there are a few factors in this but it could essentially be that simple.

 

when i have time I'll see if i can take the switch out to see what it looks like and do some testing.

 

Thanks for the idea Arcasey!

Edited March 16, 2017 by gabbygenier

[arcasey]

That's a good idea that i never even though about. just figured there was maybe an easier way that someone already figured out.

 

only thing is it wouldn't need to be that complicated. We would only need one relay really if the fog light switch is a simple on/off switch. If it is and we assume its always a negative output until its turned on. we could just add a relay to swap the negative output to make it a positive output so it would always be on instead of off.

 

now there are a few factors in this but it could essentially be that simple.

 

when i have time I'll see if i can take the switch out to see what it looks like and do some testing.

 

Thanks for the idea Arcasey!

 

Yes it very well could be that simple, and if it is I'd love to know. I think that switch is just a momentary pulse switch that sends a signal to the BCM and the BCM changes the state of the fog light circuit based on receiving a pulse from the switch. Of course this only happens when the high beams are not on because the BCM turns the fog lights off when high beams are on and I really think that has come from some states have laws against more than (4) forward facing driving lights on while in forward motion. I suspect that the BCM modules aren't all that much different but I still don't understand why they didn't reprogram the new Sierras since they only have two headlight bulbs......At any rate, the main problem I've had while trying to come up with a circuit to work is one that will return to the same state no matter what state it was in when the vehicle is turned off (of course without doing any kind of programming logic). I thought about latching/impulse relays but I just couldn't come up with a good solution to make it return to the auto on state when the headlights/DRL's are on. Basically what has to happen is the circuit needs to "reset" itself when there is a loss of constant 12V+ power, i.e. when the ignition is turned off.

 

I'll give it some more thought and see if I can come up with a simpler solution.

[gabbygenier]

 

 

 

Yes it very well could be that simple, and if it is I'd love to know. I think that switch is just a momentary pulse switch that sends a signal to the BCM and the BCM changes the state of the fog light circuit based on receiving a pulse from the switch. Of course this only happens when the high beams are not on because the BCM turns the fog lights off when high beams are on and I really think that has come from some states have laws against more than (4) forward facing driving lights on while in forward motion. I suspect that the BCM modules aren't all that much different but I still don't understand why they didn't reprogram the new Sierras since they only have two headlight bulbs......At any rate, the main problem I've had while trying to come up with a circuit to work is one that will return to the same state no matter what state it was in when the vehicle is turned off (of course without doing any kind of programming logic). I thought about latching/impulse relays but I just couldn't come up with a good solution to make it return to the auto on state when the headlights/DRL's are on. Basically what has to happen is the circuit needs to "reset" itself when there is a loss of constant 12V+ power, i.e. when the ignition is turned off.

 

I'll give it some more thought and see if I can come up with a simpler solution.

I'll keep you posted on when I take the switch out to do some testing with it. Hopefully this weekend as I have a few other things to do to the truck.

 

It's wishful thinking that its going to be simple but I've heard of a few cars with the traction control being disabled that easily. So who knows.

 

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[Lamby66]

I made a circuit with a low voltage relay and two diodes to turn my fog lights on when ever the lights are on (low or high beams) allow the automatic highbeams to function (the foglight button diables this function) and allows the fog lights to be off when in running board mode.

 

The relay is used as a logic inverter. The low beam output of the BCM is a high. The logic out of the high beams is a low. The logic output for the fog circuit is a low.

 

So take the low beam output from the BCM (sorry don't have the numbers now) feed to a small relay coil. Other side of coil to ground. Take a normally open side of the relay and also feed to ground. Run the wiper of the relay to a diode (bar side aka cathode). Connect a diode (cathode) to the high beam output of the BCM. Connect both anodes from the diodes to the fog light control on the BCM.

 

I can see if I can draw a schematic if needed.

 

Hope this helps

 

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[Lamby66]

FYI... I had to solder the wires and diodes I used to brads (nails) to get them into the BCM connectors correctly.

 

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[Lamby66]

Here is the circuit I made.

 

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[arcasey]

I made a circuit with a low voltage relay and two diodes to turn my fog lights on when ever the lights are on (low or high beams) allow the automatic highbeams to function (the foglight button diables this function) and allows the fog lights to be off when in running board mode.

 

The relay is used as a logic inverter. The low beam output of the BCM is a high. The logic out of the high beams is a low. The logic output for the fog circuit is a low.

 

So take the low beam output from the BCM (sorry don't have the numbers now) feed to a small relay coil. Other side of coil to ground. Take a normally open side of the relay and also feed to ground. Run the wiper of the relay to a diode (bar side aka cathode). Connect a diode (cathode) to the high beam output of the BCM. Connect both anodes from the diodes to the fog light control on the BCM.

 

I can see if I can draw a schematic if needed.

 

Hope this helps

 

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So, with your circuit as described and depicted above, you are able to disable the fog lights using the factory switch after they have been energized by the auto headlights and then re-energize them with one more push of the fog light switch?

[Lamby66]

No, I can not disable the fog lights except by turning the light switch to marker light mode (which is what I want) if I press the foglight button the BCM then tells the truck the fog lights are on and disables the auto high beam function

 

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[arcasey]

No, I can not disable the fog lights except by turning the light switch to marker light mode (which is what I want) if I press the foglight button the BCM then tells the truck the fog lights are on and disables the auto high beam function

 

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Okay so maybe I'm confused, what exactly do you mean by "auto high beam function." Maybe my truck doesn't have this function?

[Lamby66]

My truck has the led headlights with auto dimming high beams. It is an option Sony out might not have it.

 

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So it might not have it... stupid spell check :-)

 

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[arcasey]

Okay, that's what i was thinking it was. Another useful option I missed out on along with stock headlights that were actually useful.

[Lamby66]

 

So, with your circuit as described and depicted above, you are able to disable the fog lights using the factory switch after they have been energized by the auto headlights and then re-energize them with one more push of the fog light switch?

I read this thread again. I am not really sure what the op wants here. Gabby do you want the fog lights on whenever the headlights are on (either high or low beams)? If so you have two options jumper a diode from the parking lights circuit to the fog lights... if you do this whenever the parking lights are on so are the fogs. They can not be turned off

 

Or you can do my mod and then hen you turn off your headlights with the rotary switch and place it in parking lights mode it will turn off the fog lights as well. (I needed this as I camp alot and do not want to drive in the campgrounds with my fogs on)

 

If you want the fog lights to be always on with the headlights AND be able to shut them off with the factory switch, I would have to look deeper into some j/k flip-flop circuit to toggle the state. Using the circuit I designed but then using the fog light logic low as a "reset" for the flip-flop. It should work but seems like more work than its worth to me..

 

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[arcasey]

My understanding of what the OP wants is for the fog lights to be auto on with the headlights (high or low beam) and then be able to change the state of the fog light circuit (i.e. cycle the lights on or off) by pressing the factory fog light switch. The circuit would need to reset itself to the "original state" once the vehicle was turned off so that the fog lights would be auto on with the head lights the next time the truck was turned on. We were assuming that the factory fog light switch is a momentary pulse type switch.