4s-fe Ecu Pinout Here
| 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) |
The 4S-FE ECU (especially 89661-20450) uses Japanese capacitors from the late 80s that leak. Open the ECU case. Look for brown goo, swollen caps, or corroded traces near the power supply pins (A1, A2). Symptoms: 4s-fe ecu pinout
The 4S-FE uses a simple diagnostic system. Jump pins TE1 (B11) to E1 (A3) with the engine off. Turn key ON. The check engine light (pin A15 or B12) will flash codes. | Pin | Wire Color | Function |
| Pin | Wire Color | Function | Signal Type | Voltage/Note | | :--- | :--- | :--- | :--- | :--- | | C1 | White | Distributor NE+ (Crank angle) | AC sine wave | 0.5V – 5V depending on RPM | | C2 | Red | Distributor NE- (Sensor ground) | 0V | Shielded wire ground | | C3 | Blue | Distributor G1 (Cam position) | AC sine wave | TDC Cylinder #1 | | C4 | Yellow | Distributor G2 (Cam position) | AC sine wave | TDC Cylinder #4 | | C5 | (Empty) | N/A | N/A | N/A | | C6 | Violet | Air Conditioning (A/C) Request | +12V (AC ON) | Tells ECU to raise idle | | C7 | Light Green | Power Steering Oil Pressure Switch | Ground (when turning) | Idle-up signal | | C8 | Black | Diagnostic Port (TE1) | Ground via diag box | Jumper TE1 to E1 for codes | | C9 | White-Black | Diagnostic Port (E1) | Chassis ground | Common diagnostic ground | | C10 | Black-Red | VSV (EGR or Purge) | Ground switched | Emission control | | C11 | Red | Electric Fan Relay | Ground switched | Turns on radiator fan | | C12 | Pink-Blue | Speed Sensor (SPD) | 5V square wave | From combination meter | | C13 | (Empty) | N/A | N/A | N/A | | C14 | Red-Blue | +12V Main (IG SW) | +12V (Key ON) | Wakes up the ECU | Symptoms: The 4S-FE uses a simple diagnostic system