6. Splicing 4A-FE for Engine Swaps (e.g., 4A-FE into older Corolla/Starlet)
Camshaft and Crankshaft position signals (often from the distributor on 4A-FE).
Output signal to trigger the air conditioning compressor clutch relay 3. Critical Wiring Subsystems Explained The Ignition Loop (IGT & IGF) The 4A-FE cannot run without the and IGF loop.
Fig. 2: Computer Engine Control (1.6L 4A-FE) (Grid 4-7) - Scribd toyota 4afe ecu pinout
Below is a comprehensive breakdown of the standard functions found across typical 4A-FE MAP-sensor-based ECUs. Note: Exact pin locations vary by part number; always verify with a digital multimeter (DMM) before applying power. Power and Ground Pins
A: You lose learned idle trim and fuel trims. The ECU will run in “safe mode” for 10-15 minutes of driving. This does not affect the pinout; all signals remain the same.
| Pin | Wire Color | Signal Name | Function | | :--- | :--- | :--- | :--- | | | Red | +B1 | Main EFI Relay Power Input | | A02 | Red | +B | Main EFI Relay Power Input | | A03 | Black/Yellow | IGSW | Ignition Switch ON Signal (12V) | | A04 | - | - | Empty | | A05 | Brown | VTA | Throttle Position Sensor (TPS) Signal | | A06 | Light Green | VCC | TPS Sensor 5V Reference | | A07 | Black | E2 | TPS Ground | | A08 | Blue/Red | PIM | MAP Sensor Signal (0-5V) | | A09 | Red/Blue | THW | Engine Coolant Temp (ECT) Signal | | A10 | White/Black | STA | Starter Signal (from ignition switch) | | A11 | Light Green/Black | VC | Common 5V Sensor Reference | | A12 | Green/Red | VAF (or MAP Sig) | Early models: AFM signal | | A13 | Yellow/Red | KNK | Knock Sensor Signal | | A14 | Red/White | SP1 | Vehicle Speed Sensor (VSS) Input | | A15 | Black/White | E01 | ECU Power Ground (to engine block) | | A16 | Black/White | E02 | ECU Power Ground (to engine block) | | A17 | - | - | Empty | | A18 | Yellow | OX1 | Front Heated Oxygen Sensor (O2) Signal | | A19 | Black/Red | VSV EGR | EGR Vacuum Switching Valve Control | | A20 | Brown/Yellow | ISC1 | Idle Speed Control Valve Coil 1 | | A21 | Brown | ISC2 | Idle Speed Control Valve Coil 2 | | A22 | Light Green/Red | G- | Distributor Pickup Coil (Negative) | | A23 | Light Green | G+ | Distributor Pickup Coil (Positive) | | A24 | Red | NE+ | Distributor RPM Signal (Positive) | | A25 | White | NE- | Distributor RPM Signal (Negative) | | A26 | White/Red | IGF | Ignition Confirmation Signal (to igniter) | Critical Wiring Subsystems Explained The Ignition Loop (IGT
Distributorless Electronic Ignition (EI) with coil packs (wasted spark system) or late-model distributor variants. ECU Style: High-density, smaller multi-plug configurations.
| Pin | Signal | Description | |------|--------|--------------| | C1 | #10 | Injector 1 & 3 common (12V from EFI relay) | | C2 | #20 | Injector 2 & 4 common (12V from EFI relay) | | C3 | EO1 | Power ground (injectors, igniter) | | C4 | EO2 | Power ground | | C5 | +B | 12V from EFI main relay (ECU power) | | C6 | +B1 | 12V from EFI relay (sensor power feed) | | C7 | M-REL | EFI main relay control (ECU grounds to activate) | | C8 | W | Check engine light | | C9 | TE1 | Diagnostic jumper (connects to TE2) | | C10 | TE2 | Diagnostic jumper | | C11 | VF | O₂ monitor / fuel trim output (to diag connector) | | C12 | E1 | ECU logic ground | | C13 | ISC1 | Idle speed control valve coil 1 | | C14 | ISC2 | ISC valve coil 2 | | C15 | ISC3 | ISC valve coil 3 | | C16 | ISC4 | ISC valve coil 4 | | C17 | HT | Heated oxygen sensor heater | | C18 | OX1 | O₂ sensor signal | | C19 | KNK | Knock sensor (if equipped) | | C20 | A/C | A/C switch signal | | C21 | FAN | Radiator fan relay control | | C22 | FC | Fuel pump relay control |
For more detailed information on the Toyota 4AFE ECU pinout, consult the following resources: Note: Exact pin locations vary by part number;
If the engine refuses to start, check these three points directly at the ECU plugs with the ignition ON:
Informs the ECU of the engine's physical position for timing. 5V Reference