yes you erased any codes by disconnecting battery
(On a 1989 model you will not get codes unless check engine light is on. And the engine must run a few minutes.... now I think that is correct. It happens that way with air sensors, and maybe other systems....)

BUT, you have a 1993 model, and it might be entirely different. What is it a 24 valve?

What books do you have to refer to ? There are some available here, so speak up.

1989 5 door montero 3.0 auto
stock original Japanese
about 200k miles