Okay got the codes checked and it threw 13, 14, 24, and 31. We cleared the codes and only 13, 14, and 24 came back. Those three correspond to a ground and the front and rear speed sensors. 31 is for the electromagnetic coil (EMC) that's inside the transfer case so hopefully that was a fluke. I looked at the parts catalog and they show left and right specifications for both front and rear speed sensors. Which do I need? I'm not ordering from Isuzu (mucho $$$) so maybe trying Rock Auto later.

Mark it was pretty cold and had been for several days while it was parked. I never had any issue with TOD prior to the light flashing, and given that I had just driven it through ice/snow/salt the morning I flew out a wiring problem seems probable.