Diagnosing either bad harness wiring or bad component

[Upanddown]

2013 Silverado crew cab LT. 195K miles.

 

The driver side lock/unlock is not function but all other locking devices are (passenger side and key fob). The door is replaced and I’m not convinced just yet the wiring is 100%. I’m having a hard time identifying where the wires terminate into the fuse block.

 

There are 5 terminals on the switch with wires going to each except the middle terminal. I’ve take everything apart down to the circuit board. It was very dirty and doesn’t feel right when I try it. Cleaned it up and still doesn’t work. I have verified the fuse is good.

 

The issue could very well be both components. 

 

How would I diagnose which part, or both, needs to be replaced?

 

Thanks