How do you reset the ECU on a 1993 3000GT SL?

To reset the ECU on a 1993 Mitsubishi 3000GT SL, first, disconnect the negative battery terminal and wait for about 10-15 minutes to allow any residual power to dissipate. Then, reconnect the negative terminal. This process will clear any stored trouble codes and reset the ECU to its default settings. If needed, you can also use an OBD-I scanner to clear codes more effectively.