2009 Scion xB Really Weird Power Door Lock Gremlins

My otherwise great 2009 Toaster (145k) has had an issue with the power door locks for the past year or so. They seem to work completely at random and no two days are the same.

Some days, all of the locks will work. Some days, only one, two, or three of the doors will work. Sometimes, if I repeat the lock/unlock cycle a few times, one or more doors will start working or stop working. It is usually event different when I lock the car in the morning to go into work, and when I unlock it after work 8-10 hours later.

When they work, they work fine. The actuators seem strong. There are no noticeable sounds (grinding noises, whiney sounds, etc.) coming from the locks.

There is no difference whether I use the remote, the power door lock switch on the driver’s side, or on the passenger’s side.

I’ve checked the fuses (they’re fine). Before go to a mechanic, I wanted to see if there were any other thoughts.

Thanks in advance!

I would first suspect the switch that controls the action of the locks as the source of the trouble.