: 4A-GE (AE92/AE101), 3S-GTE (Gen 2/3), 1UZ-FE (Early LS400), 7M-GTE. The Grey Plug Era (Mid 1990s – Early 2000s)
The Engine Control Unit (ECU) is the brain of your Toyota vehicle. Among the various ECU families produced by Toyota, part numbers starting with are the most common. Whether you are performing an engine swap (like dropping a 1JZ or 2JZ into a different chassis), troubleshooting a misfire, or wiring a standalone piggyback system, having an accurate 89661 ECU pinout is critical.
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)
| | Pin | Name | Label / Function | | :--- | :--- | :--- | :--- | | Connector A | A15 | G1 | Power Ground | | | A20 | IGT | Ignition Timing Signal | | Connector B | B4 | KNK | Knock Sensor Signal | | | B6 | OX | Oxygen Sensor Signal | | | B9 | E2 | Sensor Ground | | | B11 | VTA | Throttle Position Sensor Signal | | | B12 | IDL | Idle Switch Signal | | Connector C | C1 | VC | +5 Volt Sensor Power | | | C2 | VS | Throttle Switch Signal (Full throttle / A/C cut) | | Connector D | D4 | BRS | Brake Switch Signal | | | D9 | VSS | Vehicle Speed Sensor Signal |
The Toyota 89661 part number prefix denotes an Engine Control Unit (ECU) manufactured by Denso for Toyota and Lexus vehicles. Because this part number spans across multiple decades, engines, and generations—ranging from the legendary 1990s 1JZ/2JZ platforms to modern VVTI systems—identifying the correct pinout is critical for engine swaps, diagnostics, and wiring repairs. toyota 89661 ecu pinout
Toyota and Denso evolved their ECU connector types over the years. Pinouts are generally categorized by the number of yellow or grey plastic plugs and the total count of pins. Yellow Plug Era (Late 1980s – Mid 1990s)
This pinout from a 1988-89 Corolla AE92 GTS (4A-GEL) provides a great example of the level of detail you can find for some older ECUs. It's organized into three connectors: T, U, and V.
Toyota uses a standardized set of acronyms across almost all wiring diagrams. When reading an 89661 pinout, look for these critical labels: Power and Ground Signals
Toyota uses a standardized 10-digit part numbering system. The first five digits () signify that the component is a computer assembly for engine control. The final five digits define the specific engine generation, vehicle model, transmission type, and market destination. Example: 89661-3A490 89661: Computer, Engine Control. : 4A-GE (AE92/AE101), 3S-GTE (Gen 2/3), 1UZ-FE (Early
Example: 89661 - 3A590 └─┬─┘ └─┬─┘ Product Code Specific Vehicle/Engine Match
If you reply with your number, I can narrow it down to a specific family (e.g., V6 Camry, 4-cylinder Corolla, Tundra V8) and give you typical pin functions for that generation.
Regardless of the year, Toyota maintains a highly consistent naming convention for the labels printed directly on the ECU circuit board (PCB). If you open the metal casing of an 89661 ECU, you will find these abbreviations stamped next to the solder joints. Power Supply & Ground
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 Whether you are performing an engine swap (like
High risk of frying the ECU if the wrong diagram is used (especially with 12V vs. 5V pins).
When modifying an 89661 harness, avoiding these common errors will prevent frying the computer:
The 89661 prefix identifies the core Engine Control Unit (ECU) across various Toyota models (e.g., Camry, Corolla, Land Cruiser). The subsequent digits (e.g., 89661-50241) specify the exact vehicle and engine configuration.