lights-on warning buzzer mod

[wgirardot]

I have a solution to alert you that your lights are still on after you stop and forget to turn the lights off: wire a cheap ebay piezo buzzer on your fuse box with the positive lead connected to the license plate light fuse, and the black lead connected to the fuel pump fuse................problem solved !

Hope this helps with an annoying issue that I guarantee we all experience

Bill

[porschedude996]

Please explain the path to ground for the piezo-electric buzzer. Is the ground path through the pump?

[wazzz]

Probably. When the engine is running and the pump is running, the fuel pump fuse is hot (power, +12V), and so is the positive lead of the piezo if lights are on. Therefore 0 volt at the piezo and it doesn't sound as long as engine is running. But once engine is stopped, if lights are on, piezo gets its ground through the pump and rings until you shut off the lights.
Piezo draws a small current when compared to what current is drawn by fuel pump. This is what makes this possible.

[porschedude996]

Originally Posted by wazzz

Probably. When the engine is running and the pump is running, the fuel pump fuse is hot (power, +12V), and so is the positive lead of the piezo if lights are on. Therefore 0 volt at the piezo and it doesn't sound as long as engine is running. But once engine is stopped, if lights are on, piezo gets its ground through the pump and rings until you shut off the lights.
Piezo draws a small current when compared to what current is drawn by fuel pump. This is what makes this possible.

That is what I surmised.

[thetorch]

Another solution is wiring the light circuit on a relay, triggered by any key on circuit. Your lights go off when you remove your key.

Or a delay off relay, which I added to my interior lights so if the door stays open, the dome lights go off after 2 minutes instead of draining my battery.

[PeteKz]

Delay off relay--thanks for the suggestion. Where did you get it?

[thetorch]

Originally Posted by PeteKz

Delay off relay--thanks for the suggestion. Where did you get it?

Amazon. It's programmable, you can set delays, triggers, etc.

Constant power draw is tiny (800 μA), has an even lower power mode, but that's overkill. By my math it would take years to drain a normal car battery if you never started your car. Been using for over a year.

https://www.amazon.com/gp/product/B015Z2EQCU

documentation: https://timers.shop/

[wazzz]

This one is specifically made for dome light control: https://timers.shop/Universal-Dome-Light-Dimmer-configurable-via-phone_p_46.html

[PeteKz]

thetorch--thanks.

[spuggy]

Originally Posted by wgirardot

I have a solution to alert you that your lights are still on after you stop and forget to turn the lights off: wire a cheap ebay piezo buzzer on your fuse box with the positive lead connected to the license plate light fuse, and the black lead connected to the fuel pump fuse................problem solved !

Hope this helps with an annoying issue that I guarantee we all experience

What year car do you have? My '77 got a warning buzzer from the factory; IIRC, lights on with ignition off and open the door, buzzer sounds.

They may die/get weak/be removed by a PO, however (mine was so weak it couldn't be heard without some of the instruments removed - was replacing the flasher relay at the time).

[wgirardot]

Originally Posted by spuggy

What year car do you have? My '77 got a warning buzzer from the factory; IIRC, lights on with ignition off and open the door, buzzer sounds.

They may die/get weak/be removed by a PO, however (mine was so weak it couldn't be heard without some of the instruments removed - was replacing the flasher relay at the time).

It's a '82 SC ( also did this mod on my previous '82 SC ). Tired of walking back to my car only to discover my lights on.


Bill