Door lock issue
The door switches are simple grounding circuits. When the lock button is pressed, the red/black wire from the BCM is grounded, telling it to send power to the door locks to lock the doors. When the unlock button is pressed, the orange/black wire from the BCM is grounded, telling it to reverse the power to the door locks to unlock the doors.
Have you done any recent repairs or modifications involving the BCM or the door locks (e.g. window motor replacement)?
On the other hand, if you actually mean the buttons on the key fob... it's not worth spending the time diagnosing or fixing unless you just want to open it up and check for debris or something that might be causing the external button to press only the lock button on the circuit board. Otherwise, just but a replacement and program it.





