4s-fe Ecu Pinout ((top)) 【Must Watch】

The smell of burnt clutch and desperation hung heavy in the air of the garage.

Connector “A” – 16 Pins (Sensors & Power)

| Pin | Wire Color | Function | Signal Type | Condition (Key ON, Engine OFF) | |-----|------------|----------|-------------|--------------------------------| | A1 | Black/Red | Battery Power (BATT) | 12V Constant | Always ~12V | | A2 | Black/Orange | Main Relay Power (+B) | 12V Switched | 12V when key ON | | A3 | White/Black | ECU Ground (E1) | Ground | <0.5V to chassis | | A4 | Brown | Sensor Ground (E2) | Ground | <0.1V (reference) | | A5 | Red/Blue | Throttle Position Sensor (VTA) | Analog 0-5V | ~0.5V (idle) to ~4.5V (WOT) | | A6 | Green/Black | Manifold Absolute Pressure (PIM) | Analog 0-5V | ~2.5-3.0V (sea level) | | A7 | Yellow/Green | Intake Air Temp (THA) | Resistance/Variable | ~2.0-3.0V at 20°C | | A8 | Blue/Yellow | Engine Coolant Temp (THW) | Resistance/Variable | ~2.0V cold, ~0.4V hot | | A9 | Pink | Oxygen Sensor (OX) | 0-1V Analog | N/A (engine running: 0.1-0.9V) | | A10 | White | Starter Signal (STA) | 12V Trigger | 12V while cranking | | A11 | Black/Yellow | Ignition Switch (IG SW) | 12V Input | 12V in ON/START | | A12 | Red/White | Neutral Start Switch (NSW) | Ground/12V | 0V in P/N (A/T) or clutch in (M/T) | | A13 | Blue/Red | Air Flow Meter (not used – MAP only) | N/A | N/C on 4S-FE (MAP based) | | A14 | Green/White | Knock Sensor (KNK) | AC signal | ~0V idle, ~0.5V under knock | | A15 | Light Green | Check Engine Light (W) | Output (Ground) | Sinks to ground when fault exists | | A16 | Yellow | Vehicle Speed Sensor (SPD) | Digital pulse | 0-5V pulses (4 pulses per rotation) | 4s-fe ecu pinout

Step 1: Check ECU Power (Pin A1 & A2)

• Probe A1 to A3. Should read battery voltage (12.3-12.6V). If not, check 7.5A EFI fuse.
• Turn key to ON. Probe A2 to A3. Should read 12V. If not, check the main EFI relay (engine bay fuse box).

• This pinout is for a basic 4S-FE engine ECU. There might be variations depending on the specific model year, trim, or region.
• Consult a repair manual or wiring diagram for your specific vehicle for more detailed information.
• Some signals might be missing or different depending on the ECU revision.

Connector C (12-pin – Check Engine & Diagnostics)

| Pin | Code | Function | | :--- | :--- | :--- | | C7 | W | Check Engine Light (MIL) | | C8 | TE1 | Diagnostic Jumper (for blinking codes) | | C9 | TE2 | Diagnostic Test Mode | | C10 | E1 | Diagnostic Ground | The smell of burnt clutch and desperation hung

Common Failure / Tuning Notes

• No start – check +B and +BM (B1, C15), also IGF (B10) from igniter.
• Rough idle – ISC1/ISC2 (C13, C14) open or short; clean idle valve.
• Rich/lean codes – verify VTA (B17) and PIM (B20) voltages.
• O2 sensor – VF1 (C6) should cycle 0.1–0.9V at warm idle.
• Fuel pump not priming – FC pin (B22) should ground briefly at key-on.

The search results were a minefield of broken links, paywalls, and forum posts from 2003. But finally, deep in a forgotten thread on a JDM enthusiast forum, he found it. A grainy, scanned image of a wiring diagram. It was titled simply: Toyota 5S-FE / 4S-F ECU Pinout Identification. Probe A1 to A3