4s-fe Ecu Pinout

| 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) |

Clearing codes: Remove the EFI fuse (15A) for 30 seconds or disconnect battery.

Before you start probing wires, it is essential to identify which ECU version you have. While the 4S-FE was used for several years, the most common ECU found in aftermarket swaps and popular models (like the ST202 Celica or T190 Corona) usually utilizes the Toyota 26+16+12 Pin configuration. 4s-fe ecu pinout

This setup consists of three plugs plugged into the ECU:

Note: Always check the sticker on your ECU (e.g., part numbers starting with 89661-) to confirm the diagram, as JDM variants can differ slightly from market to market. | Pin | Wire Color | Function |

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 | Signal | Description | |------|------------|--------|--------------| | B1 | B-R | +B | Battery power (EFI main relay) | | B2 | B-Y | +B1 | Battery power (injectors, sensors) | | B3 | B-O | E1 | Power ground (ECU) | | B4 | B-W | E2 | Signal ground (sensors) | | B5 | R | #10 | Injector 1 | | B6 | L | #20 | Injector 2 | | B7 | Y | #30 | Injector 3 | | B8 | L-B | #40 | Injector 4 | | B9 | W | IGT | Ignition timing signal to igniter | | B10 | R-L | IGF | Ignition confirmation from igniter | | B11 | G | G- | Distributor G signal (-) | | B12 | G-R | G+ | Distributor G signal (+) | | B13 | W | NE+ | Distributor NE signal (rpm) | | B14 | B | NE- | Distributor NE signal (-) | | B15 | B-O | STA | Starter signal (from ignition switch) | | B16 | G-W | NSW | Neutral start switch (auto) / clutch switch (manual) | | B17 | R-B | VTA | Throttle position sensor (TPS) signal | | B18 | B-Y | VC | TPS 5V reference | | B19 | G-B | IDL | Idle switch (closed throttle) | | B20 | L-R | PIM | Manifold absolute pressure (MAP) | | B21 | - | - | Not used | | B22 | G-R | FC | Fuel pump relay control | Before you start probing wires, it is essential

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

Pro tip: Download the specific wiring diagram from Toyota’s TIS or use a quality aftermarket manual (e.g., Haynes #92043) for your exact chassis number.

| Pin | Wire Color | Function | Signal Type | Voltage/Note | | :--- | :--- | :--- | :--- | :--- | | B1 | Gray | Throttle Position Sensor (VTA) | 0.3 – 4.8V | Closed = 0.3V / WOT = 4.8V | | B2 | Green | TPS Reference Voltage (VC) | 5V ± 0.1V | Supplied by ECU | | B3 | Brown | TPS Ground (E2) | 0V | Sensor ground | | B4 | Red-Yellow | Intake Air Temp (THA) | 0.5 – 3.5V | Cold = high voltage | | B5 | Blue-Black | Engine Coolant Temp (THW) | 0.2 – 3.5V | Hot engine = ~0.5V | | B6 | (Empty) | N/A | N/A | N/A | | B7 | Black-Blue | MAP / VAF Sensor (PIM) | 1.5 – 4.5V | Idle = 1.5V / WOT = 4.0V | | B8 | Green-Red | MAP/VAF 5V (VCC) | 5V | Sensor power | | B9 | White-Black | MAP/VAF Ground (E2) | 0V | Sensor ground | | B10 | Black-Red | Idle Air Control Valve (RSC) | +12V | IACV coil #1 | | B11 | Black-Yellow | Idle Air Control Valve (RSO) | +12V | IACV coil #2 | | B12 | (Empty) | N/A | N/A | N/A |