Before the problem started did you pull the instrument and steering column terminal blocks apart.

If so did you put them back together the same way, check you didn't swap them over assuming they are both the same (they are on the Torana).

I did this and couldn't understand why nothing worked when everything did before i pulled them apart, took me days to workout what i had done, it drove me insane till i sorted it.

I know it sounds silly but you never know.