Some Australian/Euro models include a third smaller 4-pin connector for automatic transmission control (A/T). This guide focuses on the version, which is most common for swaps and diagnostics.
Found in early-to-mid 1990s models (e.g., ST190 Corona). 4s-fe ecu pinout
Always count pins from the wire side of the plug (not the ECU pins) to avoid mirroring your wiring. Some Australian/Euro models include a third smaller 4-pin
A thermistor-based signal that changes resistance based on engine temperature. The ECU uses THW to determine cold-start fuel enrichment and radiator fan activation. 4s-fe ecu pinout