[Richard]

If I get this right, the first pic shows both contactors. The second, a larger pic of the override contactor. The third, is the innards of the override contactor. I can't tell the color of the trigger wire.

Russ nailed it. I too have the pressure regulator on that line, so that is the protection mechanism to prevent high pressure from the aux pump. However I have no idea where it is set to relieve pressure. I'll have to put a guage on it and see