3s-fe Ecu Pinout Pdf May 2026

| Pin | Code | Function | Notes | | :--- | :--- | :--- | :--- | | B1 | #10 | Injector 1 (Cylinder 1) | Switched ground | | B2 | #20 | Injector 2 | | | B3 | #30 | Injector 3 | | | B4 | #40 | Injector 4 | | | B6 | VSV | EGR VSV (Vacuum Switching Valve) | | | B10 | FPU | Fuel Pump Control | |

Turn the ignition off. Find the thickest white-red wire (BATT). It should have 12V constant. Find the thick brown or white-black wires (E01, E02). These are high-current grounds for injectors.

Do you have a specific 3S-FE pinout question? Leave the year and model in the comments below (or on your favorite forum), but always verify community advice against a factory PDF. 3s-fe ecu pinout pdf

| Pin | Code | Function | Wire Color (Typical) | | :--- | :--- | :--- | :--- | | A1 | +B | Main EFI Relay Power | Black-Red | | A2 | BATT | Constant 12V Memory | White-Red | | A3 | E1 | Power Ground | Brown | | A4 | IGT | Igniter Trigger Signal | White | | A5 | NE+ | Distributor Crank Signal | Black | | A6 | G1 | Distributor G1 Signal (Cam) | Blue-Red | | A7 | THW | Water Temp Sensor | Green-Blue | | A10 | STA | Starter Signal | Black-White |

If you are reading this, you are likely wrestling with wiring harness gremlins, planning a standalone engine management upgrade, or trying to diagnose a stubborn check engine light on your Toyota. The engine in question is the legendary Toyota 3S-FE —the workhorse 2.0-liter inline-four found in the Camry, Celica, Carina E, MR2 (rarely), and several Coronas from the late 1980s through the 1990s. | Pin | Code | Function | Notes

| Pin | Code | Function | Diagnostic Use | | :--- | :--- | :--- | :--- | | C1 | VTA | Throttle Position Sensor Signal | Check for smooth voltage sweep | | C2 | VC | TPS 5V Reference | Must be exactly 5.0V | | C3 | VAF | Air Flow Meter Signal (Karman Vortex) | 3S-FE uses a Karmann vortex AFM | | C5 | OX1 | Oxygen Sensor (Front) | 0.1V (Lean) to 0.9V (Rich) | | C9 | TE1 | Diagnostic Jumper (Check Engine Light) | Connect to E1 to flash codes | | C10 | E1 | Sensor Ground | Do NOT confuse with power ground (E01/E02) | If you cannot find a PDF, or you suspect your harness has been modified, you can reverse-engineer the pinout yourself. This is tedious but foolproof.

Draw the connectors. Count the pins. Note that Toyota ECUs often have missing pins—this is normal. Find the thick brown or white-black wires (E01, E02)

Unplug the coolant temp sensor. Touch one multimeter probe to the sensor connector terminal and the other probe to an ECU pin. When the buzzer sounds, you have found THW. Mark it.