You can check it by borrowing an ECU from a similar vehicle. I don't know about Toyotas, but for Mitsubishi 6g72 engines, removing the ECU is pretty straightforward. Just unscrew and remove all connectors.

There are surplus ECU's. I don't know how good they are.

Mitsubishi ECU's can be repaired (usually nasusunog lang ang diode). Baka ganun din ang case ng sa Toyota.

Pwede naman buksan ang ECU casing to check kung may sunog or na-disconnect na part.