4A-GE, 3S-GTE (Gen 2/3), 1UZ-FE (Early), 7M-GTE.
The 89661 prefix identifies the core hardware responsible for managing fuel injection, ignition timing, and transmission shifting. For instance, a unit from a mid-90s Toyota Celsior
Because miswiring an ECU can permanently destroy its internal circuit board, never guess a pin's function. Use this systematic approach to find the verified diagram:
Camshaft position sensor signals used for sequential injection timing. toyota 89661 ecu pinout
Temperature signals for Engine Coolant and Intake Air . Pinouts for Specific Engines
: When putting a 1JZ, 2JZ, or 1UZ engine into a different chassis, you must bridge the engine harness to the new body harness using the ECU pinout.
This example from a USDM SW20 provides a detailed look at some of the most critical signals found on a typical Toyota performance ECU. 4A-GE, 3S-GTE (Gen 2/3), 1UZ-FE (Early), 7M-GTE
Injector driver circuits. In older batch-fire systems, multiple cylinders share a pin. On sequential injection setups, each cylinder gets an individual number pin matching its firing order. 4. Sensor Inputs (Analog and Digital)
Toyota ECUs evolved through three distinct physical styles from the late 1980s to the present day. Identifying your plug style is the first step to mapping the pins. 1. Yellow/Gray Plastic Connectors (Late 80s – Mid 90s)
Oxygen Sensor signal and Oxygen Sensor Heater controls. Actuator Outputs Use this systematic approach to find the verified
: Ignition Timing signals sent to the igniter/coils to trigger a spark.
A: You need the full part number (the 5 characters after the dash) and the specific vehicle model/year. Check Toyota forums for your specific ECU.
This is a classic symptom of a missing IGF (Ignition Feedback) loop or a tripped factory engine immobilizer system ( SIL , IMI , IMO pins) on newer post-1998 ECUs.
: Heavy-duty grounds for the fuel injector drivers. Engine Sensor Inputs