First off, 1989 is not an OBD 2 system.
Second Mitsubishi did not support flash programming till the early 2000s in some models, later in others. That is a vague statement but I did not feel like looking up the details.
But basically non Canbus ECUs are generally non flash.
Flash programming is where we can reprogram the lookup tables such as mixture and timing in the computers.
You can reflash any Mitsu ecu as long as its eprom and you can read the code. People have been doing it for years on DSM/3000gt/evos.
In those cars the ROM gets swapped out for a programmable EPROM that allows for remapping. At least that is the way I have been doing it. I do not know of anyone reprogramming the factory chip.
I also have an old prom burner that I have used for 15 years. That was the old read, wipe, flash real PIA to do. Real old tech compared to the way it is done now.
The Canbus is a system that multiplexes many signals over just two wires to run many functions. In Mitsus case the column switches have three wires running from the switches into a relay module that does the switching of say the lights and wipers.
The earliest Can system used in Mitsubishi were the outside rear mirrors in the 94 Diamantes.
Mercedes is the pioneer in CANBUS systems in vehicles. From the early 90s even the tail lights use Mini control units to switch the bulbs. In full CANBUS vehicles there are essentially no fuses anymore. The circuits are monitored to determine current draw and the computer determines to put out power or not to the device. Kind on neat but has taken awhile to learn how the alter some of the functions.
