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. Conclusion: Master the Pinout, Master the 4A-FE The toyota 4afe ecu pinout is more than a wiring diagram—it’s a roadmap to understanding how Toyota engineered one of its most durable engines. Whether you’re chasing an intermittent misfire, performing a standalone engine swap into a classic car, or just trying to pass emissions, having the correct pinout saves hours of frustration.
| Pin | Wire Color | Signal Name | Function | | :--- | :--- | :--- | :--- | | | White | IGT | Ignition Timing Signal (from ECU to igniter) | | B02 | Red/White | #10 | Fuel Injector Cylinder #1 | | B03 | Blue | #20 | Fuel Injector Cylinder #2 | | B04 | Yellow | #30 | Fuel Injector Cylinder #3 | | B05 | Brown | #40 | Fuel Injector Cylinder #4 | | B06 | Black/Yellow | FC | Circuit Opening Relay (Fuel Pump Control) | | B07 | Light Green | VSV (CC) | Charcoal Canister Purge VSV | | B08 | - | - | Empty | | B09 | Red/White | +BM | Backup power for ECU memory (constant 12V) | | B10 | Black/Orange | W | Check Engine Light (MIL) Control | | B11 | Blue/White | ACT | Air Conditioning Switch Signal (to ECU) | | B12 | Red/Black | ACMG | A/C Compressor Magnetic Clutch Relay | | B13 | Black | E1 | Sensor Ground (shared with TPS, MAP, etc.) | | B14 | Black/White | E03 | Injector Power Ground | | B15 | Black/White | E04 | Injector Power Ground | | B16 | - | TE1 | Diagnostic Jumper Pin (for flashing CEL codes) | toyota 4afe ecu pinout
Pins B02-B05 (injectors) are switched grounds. The ECU grounds these wires to fire the injectors. You will not see 12V here with the key on. Instead, each wire should show continuity to ground for a brief pulse when cranking. Connector C (12 pins) – Auxiliary & Diagnostics This connector handles extra sensors, tachometer, and diagnostics. A: You lose learned idle trim and fuel trims
A: The 7AFE (1.8L version) ECU has different fuel maps and ignition timing. It will run a 4AFE, but poorly—rich at idle and lean at high RPM. Pinouts are similar but not identical. Not recommended. Conclusion: Master the Pinout, Master the 4A-FE The
| 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) | Pro Tip: Pins A01 and A02 provide 12V. If your fuel pump doesn’t prime, check these wires first. Pins A15 and A16 are critical grounds—never assume chassis ground is enough. Connector B (16 pins) – Injectors & Ignition This connector handles high-current outputs.
The Toyota 4A-FE is one of the most legendary small-displacement engines ever produced. Found in icons like the Toyota Corolla (E90, E100, E110), Geo Prizm, Toyota Sprinter, and the first-generation Toyota Celica, this 1.6L 16-valve engine is known for its bulletproof reliability and surprising fuel efficiency.