How do you reset ecu on 1992 Mitsubishi diamante?

To reset the ECU on a 1992 Mitsubishi Diamante, first disconnect the negative battery terminal and wait for about 15 minutes to ensure any stored data is cleared. Reconnect the negative terminal, and then turn the ignition key to the "On" position without starting the engine for a few seconds. This process helps the ECU to reset and recalibrate. Finally, start the engine and allow it to idle for a few minutes to let the ECU relearn the engine parameters.