The issue turned out to be a disconnected wire on the 4WD switch in the transmission. To test if the switch is in working order without removing, you can put it in 4WD, and then do a continuity test between the two connectors with a multimeter. I repaired for the short term, but I'll probably end up replacing it down the road.

4WD Switch P/N: 32005-ZD30A, Part Code: 32006Q

The complete list of items used in this project, and other projects, can be found in the Parts List below.