4s-fe Ecu Pinout Page

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.

Toyota 4S-FE ECU Pinout: Complete Wiring Guide and Troubleshooting

This article provides a detailed breakdown of the 4S-FE ECU pinout, essential for wiring harness restoration, troubleshooting, or performance tuning. Understanding the 4S-FE ECU System 4s-fe ecu pinout

Disclaimer: Wire colors may vary depending on the year and specific car model (e.g., manual vs. automatic transmission). Always verify with a multimeter. 10-Pin Connector (Power & Fuel) Description +B Switched 12V (EFI Main Relay) +B1 Switched 12V (EFI Main Relay) BATT Constant 12V (ECU Memory) FC Fuel Pump Control (Circuit Opening Relay) E01 Ground (Injector) E02 Ground (Injector) NSW Neutral Start Switch (A/T) STA Starter Signal (Cranking) ELS1 Electrical Load Signal (Taillight) ELS2 Electrical Load Signal (Defogger) 22-Pin Connector (Sensors & Ignition) Description E1 Main Ground E2 Sensor Ground VCC 5V Sensor Power (TPS/MAP) PIM Pressure Intake Manifold (MAP Sensor) THA Intake Air Temperature Sensor THW Water Temperature Sensor TPS/IDL Throttle Position Sensor (Idle Position) TPS/VTA Throttle Position Sensor (Signal) OX Oxygen Sensor Signal HT Heated Oxygen Sensor Power IGT Ignition Timing Signal (to Igniter) IGF Ignition Feedback (from Igniter) NE Engine RPM Signal (Distributor) G1 Distributor Position Signal G- Distributor Ground 16-Pin Connector (Actuators & Emission) Description #10 Fuel Injector Pulse 1 (Cyl 1 & 3) #20 Fuel Injector Pulse 2 (Cyl 2 & 4) RSC Rotary Solenoid Close (Idle Control) RSO Rotary Solenoid Open (Idle Control) FAN Radiator Fan Relay ACM A/C Cut Control 3. Critical Pin Descriptions for Troubleshooting

The most common "plot twist" for a 4S-FE owner involves the internal electrolytic capacitors Some Australian/Euro models include a third smaller 4-pin

Toyota changed wire colors over the years. The chart above reflects the most common 4S-FE pinout (1988–1992). However:

The is a reliable, 1.8-liter inline-four engine widely used in 1990s Japanese-market vehicles like the Corona, Carina, Caldina, and Vista. Whether you are troubleshooting an electrical fault, performing an engine swap, or installing a piggyback controller, understanding the Engine Control Unit (ECU) pinout is critical. Understanding the 4S-FE ECU System Disclaimer: Wire colors

Idle switch pin (found on older 3-wire or 4-wire TPS units). It signals the ECU when the throttle is fully closed so the engine can enter idle mode.

The ECU requires a +12V signal on the STA pin during cranking to enrich the fuel mixture for cold starts.

Toyota used several variations of ECUs for the 4S-FE across different chassis codes (e.g., ST180, ST190, SX80, SX90). Most commonly, you will encounter the classic yellow or gray multi-plug setup consisting of either configurations or the later generation 34-pin / 22-pin / 16-pin configurations.