Most 3S-FE ECUs use three main connectors. Let’s label them looking at the harness side (wires facing you).
These are power grounds specifically for the high-current injector drivers. Essential Sensor Inputs
These pins control the fuel injectors. On the 4S-FE, these are often "batch-fired" in pairs (1 & 3, 2 & 4). 4s-fe ecu pinout
| Pin # | Signal Name | Description | | --- | --- | --- | | 1 | EGT | Engine Ground | | 2 | IGT | Ignition Timing Signal | | 3 | IGF | Ignition Feedback Signal | | 4 | GND | Ground | | 5 | +B | Battery Voltage | | 6 | THA | Throttle Angle Sensor ( TPS) | | 7 | ODO | Odometer Signal | | 8 | ISC | Idle Speed Control | | 9 | SFT | Shift Solenoid (Automatic Transmission) | | 10 | L | Fuel Pump Relay | | 11 | W | Fuel Pump Monitor | | 12 | RCO | Resistance (Resistor) Check Output | | 13 | NE | Engine Speed Sensor (CKP) | | 14 | NTC | Coolant Temperature Sensor (ECTS) | | 15 | AFS | Air/Fuel Sensor (Oxygen Sensor) | | 16 | A/F | Air/Fuel Mixture Control | | 17 | Rx | Serial Communication Receive | | 18 | Tx | Serial Communication Transmit | | 19-26 | - | Not Used |
: Ignition Timing signal sent from the ECU to the ignitor. Most 3S-FE ECUs use three main connectors
The 4S-FE Engine Control Unit (ECU) pinout functions as the critical interface between the engine's sensors and the computer that manages fuel injection, ignition timing, and idle speed. Since the 4S-FE was primarily found in JDM models like the and Carina , documentation often relies on shared Toyota terminal abbreviations. Technical Overview
Connector C (C1–C13)
If you have no power at the +B pin, check your EFI fuse and the EFI relay.