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Found in the AE111 Corolla. Often features a distributorless ignition system (DIS) with coil packs or a highly integrated distributor, paired with newer OBD-II compliant ECUs in certain markets. 2. Common Toyota 4A-FE ECU Plug Configurations
These inputs tell the ECU how much air is entering the engine and how much load it is under. Function Description Voltage Range / behavior Pressure Intake Manifold MAP sensor signal input (0-5V scaled to vacuum) VCC 5V Sensor Reference Power Output from ECU to power the MAP and TPS sensors VTA Throttle Position Sensor (TPS) 0.5V (closed) to 4.5V (Wide Open Throttle) IDL Idle Switch Tells ECU the throttle is closed for idle control THW Water Temperature Signal From the Coolant Temperature Sensor (ECT) THA Intake Air Temperature Signal From the IAT sensor inside the intake piping OX1 Oxygen Sensor Signal Fluctuates between 0.1V (lean) and 0.9V (rich) Actuators and Outputs
The input from the Manifold Absolute Pressure (MAP) sensor. Voltage rises as engine vacuum drops (higher load).
| Symptom | First Pin to Check | Expected Reading | |----------|--------------------|-------------------| | No start, no CEL with key ON | Pin A1 (B+) | 12V | | Fuel pump doesn’t prime | Pin A19 (FC) | 0V for 2 sec, then open | | CEL stays on, no codes | Pin A2 (Main relay) | 12V at relay coil | | Rough idle, surges | Pin A9 (PIM) | 3.5V at idle, steady | | No power above 4000 RPM | Pin A12 (IGt) | Clean square wave to 5V | | Check engine light won’t flash codes | Jump TE1 (A20) to E1 (A22) | Must be solid ground | toyota 4afe ecu pinout
Ensure 12V is present when the key is in the "On" position.
Stepper motor or solenoid signals for controlling engine idle speed. Starter Crank Signal
Camshaft position negative signal. EGW: Exhaust gas warning. SPD (Speed): Vehicle Speed Sensor (VSS) input. TE1/TE2 (Diagnosis): Diagnostic terminal connector. OX (Oxygen Sensor): Oxygen sensor signal. Key Signals for Troubleshooting Found in the AE111 Corolla
This plug links the ECU to the vehicle’s fuse boxes, ignition switch, and battery. Pin Name / Function Description Constant Battery Power
If you are dealing with a 1990s Corolla, the Toyota Corolla 1.6 ECU wiring diagram on Slideshare can provide a reliable visual reference.
Ground , E01 , and E02 permanently to the clean negative battery terminal structure. Common Toyota 4A-FE ECU Plug Configurations These inputs
A: The ignition signal from the ECU to the igniter is often labeled IGT (sometimes marked as IGT or IGT1). The feedback wire from the igniter is IGF . The color of the IGT wire varies but is often white or yellow. You can use a multimeter on these pins to check for a signal when cranking.
MAP-based system with a streamlined intake manifold.
: The official Toyota 4A-FE Engine Repair Manual contains deep-dive circuit descriptions and sensor testing procedures.