Toyota ECUs generally fall into three design eras. Identifying your era helps narrow down the correct pinout map. The Yellow-Plug Era (Late 1980s – Late 1990s) : 4A-GE, 3S-GTE, 1UZ-FE (early), 1JZ-GTE.
| Pin No. | Symbol | Description | Wire Color (Typical) | | :--- | :--- | :--- | :--- | | | Ground | ECU Case/Signal Ground | Brown/White | | E2 | Ground | Sensor Ground | Brown | | E01 | Power Ground | Injector/Actuator Ground | Brown | | E02 | Power Ground | Injector/Actuator Ground | Brown | | BATT | Battery Power | Constant 12V (Keep Alive Memory) | Black/Red | | +B | Main Relay | Switched 12V Power (Main) | Black/Orange | | +B1 | Main Relay | Switched 12V Power (Backup) | Black/Orange |
If you have an unknown ECU and no internet, you can map it yourself: toyota 89661 ecu pinout
The ECU usually has three connectors (often labeled E11, E12, E13 or simply arranged as rows).
These standard Toyota abbreviations are typically found on the internal circuit board or in wiring manuals: Power & Ground: : Switched +12V power from the EFI main relay. : Constant +12V battery power for memory. : Switched ignition power. E01 / E02 / E1 : Main ECU grounds. : Sensor ground return. : 5V reference output for sensors (TPS, MAP). Engine Signals: #10, #20, #30, #40 : Fuel injector drive signals. IGT / IGT1-6 : Ignition timing signals sent to the igniter. : Ignition confirmation signal from the igniter. NE / NE+ / NE- : Crankshaft position sensor signal. G1 / G2 / G- : Camshaft position sensor signals. Sensor Inputs: : MAP or MAF sensor input. : Engine coolant temperature (ECT) sensor input. : Intake air temperature (IAT) sensor input. : Throttle position sensor (TPS) and idle switch signals. OX / OX1 / OX2 : Oxygen sensor inputs. Example Pinout Configurations Toyota ECUs generally fall into three design eras
: Ignition Timing signals sent to the igniter/coils to trigger a spark.
Connect your ignition key switched 12V to IGSW . | Pin No
Communications & diagnostics:
When looking at a factory Toyota service manual for an 89661 ECU, you will encounter standard abbreviations. Use this reference table to decode your specific board layout: Abbreviation Function Description Injector Fire Signals Triggers the grounding circuit to open fuel injectors. IGT (1, 2, 3...) Ignition Timing Output signal from ECU to igniter to trigger spark. IGF Ignition Feedback Confirmation signal sent back from the igniter to the ECU. NE+ / NE- Crankshaft Position Engine speed signal from the crank sensor. G1 / G2 / G+ Camshaft Position Identifies cylinder position for sequential injection. VCC 5V Sensor Power Clean 5V power supply output from ECU to sensors. VTA Throttle Position Analog voltage input from the Throttle Position Sensor. PIM / VG MAP / MAF Sensor Manifold Pressure (PIM) or Mass Airflow (VG) input. THW Water Temperature Input from the Engine Coolant Temperature (ECT) sensor. THA Intake Air Temp Input from the Intake Air Temperature (IAT) sensor. OX1 / HT1 Oxygen Sensor O2 sensor signal input (OX) and heater control (HT). FC Fuel Control Triggers the circuit opening relay to run the fuel pump. SPD Speed Signal