This is likely an issue with the wiring at the body control module. I will try to explain how it works. When you press lock, power flows one direction causing the actuators to react in a specific direction. When you press unlock, power flows in a different direction causing the opposite reaction by the actuator.
Now, if you look at the attached pics, I highlighted the wires that are responsible for unlocking the doors. They go from the switches to the body control module (pic 1). What needs to be done is to first check the connection at the BCM and make sure it is not loose or corroded where the plug attaches to it.
Next, see if there is power being sent to the switch via the wires highlighted. If there is power, then the ground, which has a splice in it, needs checked. Note that the ground is for both lock and unlock, but two wires go to one ground. They are spliced together. There is a chance that the unlock ground has failed but the lock ground is still good. (Pic 2)
I know this sounds confusing, but let me know if you have questions or need help.
Images (Click to enlarge)
Thursday, December 17th, 2020 AT 12:12 PM