the under hood fuse box has relays that can be replaced like fuses . with this GM change it appears some can not be changed because they are soldered to the fuse board.Ok, so it does. And, every other relay in the underhood fuse panel is mounted to the PCB (printed circuit board). The identified (owner's manual) relays are plugged into sockets that are mounted to the PCM, this one apparently is not socket mounted.
@j cat, your the expect, where is it mounted/located?
PCM has relays these are also soldered in . this problem is most likely with the PCB of the under hood fuse box.
removal would require battery disconnect. then removing the fuse box mounting screws cover etc... then you have connectors under the box to sort out..
this fuse box is used by rodents to make nest. they chew up the wires under there.