The harness that runs through the shifter stem has a tendency to rub through from being moved so much when shifting. Most likely it has rubbed through. You can remove the column cover and inspect it. You can also disconnect the connector and check the switch with an ohm meter. Check all fuses also of course but thats usually the cause.
I have an MPV 2000, and am having the same problem for the O/D button, it only turns on in P, and sometime in N as well. Please let me know what you find on yours. Car drives fine, O/D works fine if I can switch it on. So, I too am suspecting the colume, anyone knows how to take the colume cover out? thanks.
________ Magic flight
I just bought a 2003 MPV and the OD button does not work and no OD light comes on. How do I tell if the tranny is shifting into the 5th gear? How many RMP's is the MPV supposed to run at 100km/hr (or 62miles/hr). At this moment it is revving at 2100rmp @ 100km/hr. Am I in fifth gear? Thanks