i believe that the codes are very similar if not the same between the 7mgte and the 1jzgte. i know a 31 is the air flow meter signal on the 7m, which is the equivelant to the map on the 1j.
a lot of the codes are very similar between the 7M and the 1jz, but if you go to the tech articles section at www.mkiv.com, look under the OBD I engine codes and those are what you need code for code.