FYI FORD MustangSteve's Ford Mustang Forum / Lights on reminder

**Posted by John Ha** 2/21/2021 11:23 AM

I’ve left my lights on too many times and came up with a circuit that I could add to a vehicle that does not have a lights on reminder to help me remember when I leave the lights on. In essence, a tone sounds when the door is opened and the lights are on. I also added a “shutup” switch that can be used to turn the alarm off in the event that the door must be open with the lights on.

I added this feature to quite a few of my vehicles over the years and it’s saved me quite a few times. There are two variations of the circuit - this one for vehicles that apply power to the interior courtesy lights when the door is opened and another (not shown here) for vehicles that apply ground to the courtesy lights when the door is opened.

**Posted by HudginJ3** 2/21/2021 3:26 PM

I put one one my mustang while I was redoing the A/C. Works good. I need to put in that on - off switch but I"d probably forget to turn it back on. I got the factory reproduction part. It's not very noisey as the reports say.

**Posted by John Ha** 2/22/2021 12:02 PM

HudginJ3 wrote:
but I"d probably forget to turn it back on.

You don't need to turn this one back on. It "rearms" itself when the door closes.

**Posted by Nos681** 3/07/2021 8:37 AM

Thanks, I may have to make one for wifey’s F150.

I don’t care for buzzers and dingers and all of that noise besides the stereo.

I may cut in a relay that will only allow lights on when ignition switch is on.
Figure that’s a carryover from the days of burnt up points and being able to have lights on.

Last edited by Nos681 (3/07/2021 8:45 AM)

**Posted by markdtn** 5/20/2021 9:08 AM

Another simple version of this also uses the common SPST "Bosch Style" cube relay. It does not have the override and sounds with door open or closed. It would be terminal 85 to ground, terminal 86 to ignition. Terminal 30 to marker lights and terminal 87A out to the hot side of your chosen buzzer/beeper/dinger. (If you want to be able to have parking lights only on with ignition off and no buzzer-thus a headlight only reminder-then terminal 30 would go to the wire between the headlight switch and dimmer switch.)

Theory of operation: When the ignition is on, the relay goes to the unpopulated Normally Open side so the buzzer does not sound-whether or not the headlights are on. When the ignition is off and the headlights are off, the buzzer does not sound. But when ignition is off and headlights are on , then the buzzer receives power through the Normally Closed side of the relay.

Last edited by markdtn (5/20/2021 9:09 AM)

**Posted by John Ha** 6/05/2024 7:38 AM

markdtn wrote:
Another simple version of this also uses the common SPST "Bosch Style" cube relay. It does not have the override and sounds with door open or closed.

See the 4th bullet in the notes at the bottom - delete the "shutup" and keep the spst relay. Still works when lights on, door opens but can't be silenced unless lights are turned off or door is closed.