External lock/unlock button

HelpNeeded · August 7, 2023

I decided to put a hidden lock/unlock button outside my vehicle. I did this for several reasons such as:

lock the door when running into QT and leave truck running to stay cool (seems easier than turning off and remote starting)
Leave keys in the car when I don't want them in my pocket or have to worry about losing them (lake, camping, etc.)

I have been sort of successful but not really. haha. here is what I mean.

I tapped into the driver side door lock/unlock wiring where the wires enter the vehicle near the driver foot area. I ran this wire to external button that connects to ground when pressed. Awesome! Buttons work and doors lock and unlock ... until the car as been off for a while. This is where functionality seems inconsistent right now and I am thinking it is tied to some security or battery saving mechanism.

In my testing, if:

I immediately use the buttons shortly after using the vehicle, they both always work.
If it has been a while since vehicle was used, sometimes they both seem to work, sometimes just the lock, and sometimes neither.
When they are not working if I simply unlock with key fob and then try the buttons, they always have worked. This is what leads me to think there is some power saving or security setting influencing a system. When key fob is used it wakes them up and now buttons have power running to them again??? maybe?

I'm stumped right now. Happy the buttons sort of work, but it is not helpful unless I can always count on them to let me in the vehicle.

I'd appreciate any input on my current solution, things to test, or alternative ways to accomplish this. 2018 GMC Sierra

Thanks!

Edited August 7, 2023 by HelpNeeded
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