Bluebee, I believe he understood your question. You may not have understood his answer. I think it is irrelevant, but the second hole by each pin is to allow more surface area on the other side for the small pin is his guess. I do not think he is referring to the 6 slotted holes. It is some sort of "clearance" hole is his guess.
This thread is jumping around so much I think you are going to lose readers. You had a pressure switch issue- then you didn't, but you never tested your switch and I don't know how you decided to discount it.. I tested mine and it clearly is very straightforward and easy to test on the car by back probing (sticking the VOM leads into the backside of the connector). What we will never know is what rise in voltage is necessary for the module's brain to be happy. Mine swung up to just a hair over 4 VDC with full brake pressure. it was about .4VDC with no brake applied.