The closest condition that I saw in the US manual indicated that it may be your "4H switch circuit being shorted to ground".

If you can find the equivalent JDM version of the VX repair manual, that circuit and it's equivalent JDM components may be a good place to start. The flow chart for diagnosing that circuit suggested that the problem could possibly be associated with:

- a faulty TOD indicator lamp bulb
- a failed ECU
- a simple short somewhere in the circuit between the ECU and the "4H" switch
- or, a problem in the "transfer assembly"

Given some of the TOD problems I've seen and experienced on my '01 US VX, it might be worth a try to simply disconnect all of the electrical connectors on your transmission, clean both the male and female ends with an electrical cleaning spray, add some dielectric grease to the weather seals to make sure all connectors are waterproofed as well as possible, then reconnect everything and see what happens.

My TOD system flaked out big time once while driving during a very heavy rain that caused standing water. It still acted strange for awhile after the rain stopped, and when the excess water was gone, everything went back to normal. After that episode, I followed the previous steps to waterproof the connectors on my transmission, and have never had the problem again.

It'd be worth the time and effort on your own to determine if it's something simple like that before looking into more expensive repairs and having to deal with your uncooperative Isuzu dealer...in my opinion anyway.