Headlights off with the Ignition Switch

[Ryan S.]

I want to make the headlights turn off with the ignition off to prevent accidental battery drain. Has anyone done this and know how? I have the new DMC headlight switch.
Thank you

[Ryan S.]

Never mind. I think I (Google) found it. However, I am not sure if those instructions will work with the new DMC headlight switch ???

[Tillsy]

Yes, but I invented my own solution that does away with the standard headlight switch - parks always on as DRL (and circuit cut at rear and current offloaded to a relay) and headlights only require a single click and only works when in accessory or running.

I've no idea if my approach would be compatible with the newer headlight switch, I'd imagine you'd have to achieve same thing differently.

The key is eliminating the positive feed which is always on, and getting it from the ignition or aux relay at rear - no worries about pulling too much current as that headlight circuit is doing nothing more than throwing a relay that in turn carries the load of the lights.

[Bitsyncmaster]

That was designed into the new DMCH headlight switch but they found the signal (orange wire) was susceptible to noise and it could turn off your lights accidentally when driving. Not sure if they changed the software to eliminate that function now.

[David T]

That was designed into the new DMCH headlight switch but they found the signal (orange wire) was susceptible to noise and it could turn off your lights accidentally when driving. Not sure if they changed the software to eliminate that function now.

Instead of trying to turn off the lights it might just be simpler to add a buzzer so if the lights are on and the key is off it buzzes to warn you. Might be able to do it with the buzzer already in the car that warns you if the ignition is off and the key is still in the lock and the door is open.

[DrJeff]

Instead of trying to turn off the lights it might just be simpler to add a buzzer so if the lights are on and the key is off it buzzes to warn you. Might be able to do it with the buzzer already in the car that warns you if the ignition is off and the key is still in the lock and the door is open.

I upgraded to the GM Chimer and got this function, I.e. it chimes if the lights are on but the ignition off. The only hard part to wire in was the seatbelt warning light.

[Elvis]

seat belt warning light ? brrrr I ripped that sh... out of my daily driver.

For the "new" headlight switch - my solution works 100% reliable for several
years now without any negative effects. The upgrade costs less than 20
cents for 2 capacitors :-)

[Ryan S.]

So Elvis, What was your solution?
Thanks much in advance.

[Elvis]

can you solder ?


you need two capacitors with ~47nF on the two inputs of the microcontroller.

[Ryan S.]

Yes, I can.

[Elvis]

Well, sounds good to get started.

Get some caps, something between 33 to 100nF should be OK.

[Ron]

Elvis,

Very interested in your solution for the new headlight switch random failures using the caps...
I understood the problem was an unforeseen voltage drop due to aged connections, etc. (failed a comparisons), solved by moving (?or adding?) a wire directly to the battery?? BUT, in the end, the solution was to not use the auto-off feature...

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Slightly OT, but if you don't have or don't trust the new headlight switches, you could disconnect and tie the Main and Dip Beam relay ground terminals together then ground them via a relay (the unused Hot Start looks like a fair choice since everything could be done in the relay compartment...) triggered by any accessory wire (preferably on a fused light circuit for future troubleshooting ;-)