4s-fe Ecu Pinout May 2026

If you are pulling a 4S-FE ECU from a junkyard, open the metal casing. Toyota ECUs from this era (early 90s) are notorious for electrolytic capacitor failure. If you see a brown crusty substance on the circuit board, the capacitors have leaked. This can cause erratic sensor readings and phantom check engine lights.

| Pin | Code | Function | Wire Color (Typical) | | :--- | :--- | :--- | :--- | | A1 | +B | Main EFI Relay (Power) | Yellow/Red | | A2 | E1 | ECU Ground (Power return) | Brown | | A9 | STA | Starter Signal (to tell ECU you’re cranking) | Black/White | | A10 | VTA | Throttle Position Sensor (TPS) Signal | Light Green | | A11 | VC | 5V Sensor Power (for TPS & AFM) | Yellow/Blue | | A14 | THW | Coolant Temp Sensor Signal | Brown/Yellow | | A18 | IGF | Ignition Feedback (from Igniter to ECU) | White | | A20 | IGT | Ignition Timing Signal (ECU to Igniter) | Red/White | | A21 | NE+ | Distributor Crank Position Signal (+) | White | | A22 | NE- | Distributor Crank Position Signal (-) | Black |

| 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 |

The 3S-FE ECU is a robust unit from the golden era of Toyota reliability. But 30-year-old wiring gets brittle. Before you blame the ECU, check your grounds and your corrosion.

Print this pinout, tape it to your toolbox, and save yourself three hours of squinting at a blurry PDF.

Got a specific 3S-FE pinout question? Drop your ECU part number in the comments below.

Toyota 4S-FE engine, part of the S-family, was commonly found in Japanese market vehicles like the Corona, Carina, and Mark II

during the early 1990s. Since these engines often used different ECU configurations depending on the specific model and year (e.g., ST180 vs. ST190), the pinout is typically categorized by the number of pins on the ECU connectors. Common ECU Pinout Configurations Most 4S-FE ECUs feature a 3-plug design (typically 26p-16p-22p 10p-18p-14p

). Below is a guide to the primary pins you will need for wiring or diagnostics: Power & Ground : Switched 12V power from the EFI main relay. : Constant 12V from the battery (for ECU memory). E1 / E2 / E01 : Main chassis and sensor grounds. Ignition & Fuel : Ignition trigger signal to the igniter. : Ignition confirmation signal back to the ECU.

: Injector pulse signals (usually batch-fired on these older units). : Intake manifold pressure signal (MAP sensor). : Intake air temperature. : Coolant temperature. : Throttle position sensor (TPS) and idle switch. : Oxygen sensor signal.

: Crankshaft/Camshaft position signals from the distributor. ISC / ISCV : Idle Speed Control Valve.

: Fuel pump relay control (often grounds the circuit to turn the pump on). : Check engine light (MIL) output. Diagnostic Access

To retrieve error codes without a scanner, you can bridge the following pins in the "Diagnosis" box under the hood: : Bridge these with a paperclip. Ignition ON

: Count the flashes of the "Check Engine" light on the dash. Document Resources

For a detailed visual diagram, enthusiasts generally refer to the Toyota ST190/ST191 Repair Manual

Toyota Corona/Carina (1992–1996) Electrical Wiring Diagrams

. You can find community-verified spreadsheets and high-resolution photos of these pinouts on: Toyota-Club.net (Technical database for JDM Toyotas). ToyoDIY.com (Parts cross-referencing). for a particular car model, like a Corona ST190

The Toyota 4S-FE engine is a 1.8L variant of the S-series family, commonly found in JDM (Japanese Domestic Market) vehicles like the Corona (ST190) and Carina. Because it was largely a Japanese market engine, finding English-language pinouts can be tricky, but it shares significant architecture with the more common 3S-FE. 💡 Key ECU Pinout Highlights

For the 4S-FE (specifically the ST190 generation), the ECU typically uses a three-plug configuration (26-pin, 16-pin, and 22-pin). Power & Ground: B+ / +B1: Switched power from the EFI relay. BATT: Constant 12V for memory. E01 / E02 / E1: Main computer and power grounds. Ignition Signals: IGT: Ignition Trigger signal to the igniter.

IGF: Ignition Confirmation signal back from the igniter (crucial for fuel delivery). Fueling:

#10 / #20 (or #1 / #2): Injector pulse signals. Many 4S-FE units use "batch fire" injection. Sensors: PIM: Pressure Intake Manifold (MAP sensor signal). THW / THA: Water and Intake Air temperature signals. OX: Oxygen sensor signal. 🛠️ Troubleshooting & Resources

Cross-Compatibility: If you cannot find a specific 4S-FE diagram, the 3S-FE wiring from the same year and chassis is almost identical in pin assignment.

Connector Identification: Always count pins from the wire side of the plug (not the ECU pins) to avoid mirroring your wiring. 4s-fe ecu pinout

JDM Specifics: Many 4S-FE ECUs feature an "Econ" light or specific lean-burn pins if the engine is an "S-FE Lean Burn" variant. 🔗 Useful Links

General Toyota Diagrams: You can find high-resolution JDM wiring maps on Scribd's Toyota JDM Guide.

Forums: The CarTechnology forum has archived threads specifically requesting 4S-FE pinouts for the ST190 Corona. Toyota 4S-FE ecu pin out please - Printable Version

Toyota 4S-FE ecu pin out please - Printable Version. Toyota 4S-FE ecu pin out please - Printable Version. +- CarTechnoloGY (https: CarTechnoloGY Toyota Carina AT192 - 5A-FE ECU Pinout & Wiring Diagrams

The Toyota 4S-FE engine is a 1.8L inline-four from the legendary S-series family, common in 1990s models like the Corona, Carina, and Mark II. Because it shares its architecture with the more famous 3S-FE, many of its ECU pinout abbreviations and wiring logics are identical.

If you are working on a swap or troubleshooting, the most reliable way to identify pins is to look for the abbreviations printed directly on the ECU circuit board (PCB) next to the connector pins. Common 4S-FE ECU Pin Abbreviations & Functions

While specific wire colors can vary between car models (e.g., a Mark II vs. a Carina), the following terminal codes are standard for Toyota ECUs of this era: Full Name / Function +B / +B1 Switched Power +12V power from the EFI Main Relay when the ignition is ON. BATT Constant Battery Power Permanent +12V used to keep the ECU memory (DTCs) alive. E1 / E01 Main Ground The primary computer and power grounds for the ECU. E2 / E21 Sensor Ground

Dedicated ground loop for sensitive sensors to prevent electrical noise. #10 / #20 Injector Signals

Controls the ground side of the fuel injectors (usually batch fired). IGT Ignition Timing Signal sent from the ECU to the igniter to trigger a spark. IGF Ignition Feedback

A "confirmation" signal sent back to the ECU to prove a spark occurred. NE / NE- Crank/Cam Signal Engine speed (RPM) and position data used for timing. PIM Pressure Intake Manifold Signal from the MAP sensor to measure engine load. THW Water Temp Signal Engine Coolant Temperature (ECT) sensor input. THA Intake Air Temp Measures the temperature of the air entering the engine. VCC Sensor Power

5V reference power supplied by the ECU to sensors like the TPS. IDL / VTA Throttle Position

Signals for idle switch (IDL) and variable throttle angle (VTA). OX / HT Oxygen Sensor Feedback from the O2 sensor; "HT" is for the sensor heater. STA Starter Signal

Tells the ECU the engine is cranking to enrich the fuel mixture. W Warning Light Controls the "Check Engine" light on the dashboard. Pinout Configuration (26P - 16P - 22P)

Many 4S-FE models utilize a triple-connector setup. A common configuration found in 90s Toyotas like the Celica and ST202 with the S-series engine includes:

26-Pin Connector: Often contains main power (+B, BATT), grounds (E1, E01), and primary sensor inputs (PIM, THW).

16-Pin Connector: Typically handles auxiliary systems like A/C, speed sensors (SPD), and diagnostic ports (TE1, TE2).

22-Pin Connector: Frequently dedicated to ignition and fuel delivery (IGT, IGF, Injectors). Troubleshooting Tip: Checking the Board

If your harness colors don't match the diagrams you find online, unscrew the ECU casing and look at the bottom of the PCB. Toyota almost always silk-screens the pin names (like "BATT", "E1", "PIM") directly onto the board near the pins. This is the "gold standard" for ensuring you don't fry your computer during a custom wiring job. If you'd like, let me know: The exact car model and year (e.g., 1994 Toyota Corona) The part number on your ECU (e.g., 89661-xxxxx) The connector count (Is it 2-plug or 3-plug?)

Finding a verified 4S-FE ECU pinout can be tricky since these JDM engines (commonly found in the Toyota Corona, Carina, and Mark II) vary slightly by year and chassis (e.g., ST180 vs. ST190).

However, because the 4S-FE and 3S-FE share the same S-series engine architecture, their ECUs often use the same 26-pin / 16-pin / 22-pin or 12-pin / 16-pin / 26-pin connector configurations. Common Toyota "S-Series" ECU Pinout (Standard Layout)

The following pin descriptions are typical for 1990s-era S-series FE engines using a Manifold Absolute Pressure (MAP) sensor. Power & Ground Pins

BATT (Back-up Power): Provides constant 12V for the ECU memory. If you are pulling a 4S-FE ECU from

+B / +B1 (Switch Power): 12V power from the EFI relay when the ignition is ON.

E01 / E02 (Power Ground): Heavy-duty grounds for injector drivers.

E1 (Logic Ground): Primary ground for the ECU's internal logic.

E2 / E21 (Sensor Ground): Dedicated clean ground for sensors (MAP, TPS, Coolant). Signal Inputs PIM (Pressure Intake Manifold): Signal from the MAP sensor.

THW (Water Temp): Signal from the Engine Coolant Temperature (ECT) sensor.

THA (Air Temp): Signal from the Intake Air Temperature (IAT) sensor.

VTA (Throttle Position): Signal from the Throttle Position Sensor (TPS).

IDL (Idle Switch): Informs the ECU that the throttle is fully closed.

NE / G (Engine Speed/Position): Signals from the distributor/crank sensor for RPM and timing. Control Outputs

#10, #20 (Injectors): Grounding signals to fire the fuel injectors.

IGT (Ignition Timing): Trigger signal sent to the igniter to fire the coil.

IGF (Ignition Feedback): Signal back from the igniter confirming the coil fired (required to keep the fuel pump running).

ISC / ISCV (Idle Speed Control): Controls the idle air control valve.

W (Check Engine Light): Grounds this pin to illuminate the MIL on the dash. Drafting Your Post If you are sharing this on a forum or social media,

Post Title: Toyota 4S-FE ECU Pinout Reference (ST180/ST190/SX90)

Body:Hey everyone, I know how hard it can be to find solid documentation for the 4S-FE, especially for wiring swaps or troubleshooting sensor issues. Since the 4S is essentially the smaller brother of the 3S-FE, many of the pins are identical. Quick Reference for the 26P-16P-22P Layout: Need Power? Check BATT (Constant) and +B (Switched).

No Spark? Verify IGT is sending a signal and the ECU is receiving IGF.

Rich/Lean Issues? Test the PIM (MAP sensor) and THW (Coolant temp) signals.

Pro-Tip: Always verify your specific plug shape. Toyota switched between "square" and "round" terminal styles in the early '90s. If your wire colors don't match standard 3S diagrams, focus on the pin position rather than the insulation color!

Does anyone have a high-res scan for a 1994 Corona (ST190) specifically? Drop it below! #Toyota #4SFE #3SFE #ECU #Wiring #JDM #EngineSwap

For a specific diagram, you might check community threads like those on ToyotaNation or the Toyota Owners Club, where users frequently share manual scans.

Understanding the Toyota 4S-FE ECU pinout is essential for engine swaps, troubleshooting, or custom wiring. While exact pin positions can vary slightly between vehicle models (like the Toyota Corona or Carina), Toyota largely used a standardized set of terminal abbreviations and connector layouts throughout the 1990s. Typical ECU Terminal Abbreviations The 3S-FE ECU is a robust unit from

Most 4S-FE units feature printed letters on the internal circuit board next to the pins, which indicate their function. Common terminals include: Power & Ground

+B / +B1: Switched battery power (12V) via the EFI main relay. BATT: Continuous battery power for memory. E1 / E01 / E02: Main computer and power grounds.

E2: Sensor ground return (ground output for sensors like TPS and Coolant). Ignition & Fuel

IGT: Ignition trigger signal sent from the ECU to the ignitor.

IGF: Ignition feedback signal sent from the ignitor to the ECU to confirm spark.

#10 / #20: Injector pulse signals (often batch-fired for older FE engines).

NE / NE-: Engine speed (RPM) and crankshaft position signals. Sensors PIM: Manifold Absolute Pressure (MAP) sensor input. THW: Engine coolant temperature sensor input. THA: Intake air temperature sensor input. VTA: Throttle Position Sensor (TPS) signal. OX: Oxygen sensor (Lambda) input. Common Connector Configurations

Early 1990s 4S-FE ECUs often utilize a 26-pin / 16-pin / 22-pin or 26P / 16P / 12P connector setup. For the most accurate results when wiring, it is highly recommended to open the ECU casing and look for the etched labels (e.g., "STA", "IDL", "+B") directly on the PCB.

A deep dive into the 4S-FE ECU pinout!

The 4S-FE is a 1.8L inline-4 engine produced by Toyota, used in various models such as the Camry, Corolla, and Solara. The ECU (Engine Control Unit) for this engine is a complex computer that controls various engine functions, including fuel injection, ignition timing, and emissions.

Here's a detailed breakdown of the 4S-FE ECU pinout:

ECU Pinout Overview

The 4S-FE ECU has a total of 35 pins, which are divided into several categories:

Power and Ground Pins

Sensor Input Pins

Actuator Output Pins

Communication Pins

Miscellaneous Pins

Keep in mind that this is a general overview, and actual pinouts may vary depending on the specific ECU and vehicle model. Always consult the repair manual or ECU documentation for specific information.

Would you like to know more about a specific aspect of the 4S-FE ECU or have any questions about the pinout?

Unplug the TPS and MAP sensor. Turn key ON.