I suspect that Honeywell decided to save a few cents on every unit shipped by eliminating the jumper plug. The logic was probably that these are being sold for use as replacement parts and that the needed jumper plug can be pulled off the unit being replaced. That doesn't much help an installer that is using it to universally replace some other type of module.
Of the dozens of these I've installed over the years (including this variant) every single one had the jumper plug in place. It IS very disappointing to learn that they've cheaped out on a part that when missing can permanently disable the unit from functioning as required.
Here is a block diagram of what's going on inside an S8610U taken from an older manual. You can see it shows 24V connecting to Pin 1 to provide power to the damper. You can also see it shows Pin 2 providing power to the internal circuits on a call for heat.
Here is the internal schematic of an M896 Damper. It shows 24V from Pin 1 returning to Pin 2 when the damper is open.
Of the dozens of these I've installed over the years (including this variant) every single one had the jumper plug in place. It IS very disappointing to learn that they've cheaped out on a part that when missing can permanently disable the unit from functioning as required.
Here is a block diagram of what's going on inside an S8610U taken from an older manual. You can see it shows 24V connecting to Pin 1 to provide power to the damper. You can also see it shows Pin 2 providing power to the internal circuits on a call for heat.
Here is the internal schematic of an M896 Damper. It shows 24V from Pin 1 returning to Pin 2 when the damper is open.

