Identifies the component as a Toyota/Lexus Engine Control Unit.
: Cross-reference your data with official Toyota Electrical Wiring Diagrams (EWD). Reliable enthusiast databases and forums (like ToyoDIY, Club4AG, or IH8MUD) archive these documents by engine generation. 5. Best Practices for ECU Wiring and Splicing
Always protect the +B and BATT lines with appropriate fuses (usually 7.5A to 15A depending on the chassis) to shield the internal ECU logic boards from unexpected short circuits.
Ultimate Toyota 89661 ECU Pinout Guide: Wire Maps, Functions, and Troubleshooting toyota 89661 ecu pinout
: Many older Toyota ECUs have the pin abbreviations (like BATT, E1, IGT) printed directly on the circuit board next to the connector pins, accessible by removing the aluminum cover. Factory Service Manuals (FSM) : Official documentation like the Toyota Global Service Information Center (GSIC) or third-party resources like Malmatronic provide the most reliable wiring diagrams. Community Databases : For engine swaps (like the 1UZ-FE), sites like are common for finding pinouts for specific part numbers. To help you find the exact pinout, could you provide the full 10-digit part number (e.g., 89661-XXXXX) and the vehicle model Ecu pinout for 89661-3a080?
Tie E1 , E01 , and E02 together and ground them cleanly to the engine block or a solid chassis point.
This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later. Identifies the component as a Toyota/Lexus Engine Control
Typically designates the vehicle chassis or engine family generation.
The Toyota 89661 part number prefix designates the Engine Control Unit (ECU) across a massive variety of Toyota and Lexus vehicles from the late 1980s to the modern era. Whether you are performing an engine swap (like dropping a 1JZ, 2JZ, or 1UZ into a different chassis), troubleshooting a misfire, or wiring a standalone engine management system, understanding the 89661 ECU pinout is critical.
Your action plan:
If you post online for help, provide:
Many 89661 ECUs found in the share a similar pinout structure. If you are working on a harness swap (e.g., swapping a 1ZZ engine into another car), here are the critical pins usually found on the 3 connectors (labeled E7, E8, E9 usually):
Sensor ground return loop (isolated from chassis noise). Factory Service Manuals (FSM) : Official documentation like
If you cannot find a factory diagram matching your exact 10-digit part number, follow this hardware approach to locate key pins manually: