Detect my Car is locked?

So here’s the problem, sometimes in haste to unload the kids I will forget to lock the car (sssh, hopefully nobody nefarious is reading this!).
Does anyone know of any method to detect that the car has been locked?
It would be great to have the car door lock state (or alarm) as a sensor in HA.
I have scanned OBDII docs but cannot see anything helpful.

I can relate!!!
And if someone has a solution I’d love to know too, so I’ll be watching this thread…

An idea I’ve had is to somehow automate my car remote to send a lock signal at a certain time of night.
But I suspect the remote’s signal is not so easily captured. And I would rather not have to sacrifice a remote to hook something up to it’s internals.

It’s going to depend a lot on the specific car. Yes there could be some way to do it via OBD but depends if this info is sent via OBD and how to capture it.

A simpler solution may be via the use of an ESP8266 type device.

Usually when a signal is sent to the door locks it pulls down the lock/unlock to negative. So to have this trigger the ESP8266, wake up, connect to wifi, send an MQTT message and then sleep again. You could have 2 pins connected so lock and unlock is both triggered.

That way you could also be alerted if your car is unlocked in the night and/or turn on lights etc as needed.

Thanks for the replies. TBH I am worried to break into the wiring loom and find whichever wires are connected to the actuator. It’s rather intrusive and could be an expensive mistake.

I have googled and googled for a commercial solution or OBD2 solution but so far coming up empty. I can’t understand why someone isn’t making such a handy device!

So, I have been thinking and am considering a hack mechanical solution. By attaching a small microswitch to the lock pop-up button (the thing on the top of the inside door), and hacking Zigbee Xiaomi Contact Sensor to be a transmitter, maybe, just maybe that would work. The Zigbee sensor would transmit when the lock is open/closed. Although it would be somewhat unsightly and will be a problem to fasten/glue to the door internal window ledge.

Like I say I think it comes down to what information is provided over OBD. You probably can obtain this information on most cars but maybe not with the ignition off.

It would pose a security risk exposing lock information and control over OBD with the ignition off.

Your solution certainly is simple.

You can usually find workshop and wiring diagrams for most cars online if you want to go down that route.

Hi @butako123

Did you have any luck with this project?

I too am trying to find a solution to the car being left unlocked.


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