| Pin | Wire Color | Function | Signal Type | |------|------------|-----------------------------|------------------| | A1 | W-B | Battery +B (memory) | 12V constant | | A2 | B-R | ECU Ground | 0V | | A3 | B | Main Relay control (output) | 12V when ON | | A8 | R | Injector #1 | Switched ground | | A10 | Y | Ignition coil #1 | 5V digital | | B8 | BR-Y | Crankshaft position sensor (+) | AC sine wave | | B11 | B-Y | Camshaft position sensor (G2) | Hall effect | | B24 | LG-R | APP sensor (pedal position) signal | 0.6-4.5V | | C5 | W | CAN High (diagnostic line) | 2.5-3.5V | | C6 | W-B | CAN Low | 1.5-2.5V |
Toyota transitioned through several plug styles during the 89661 production run. Most hobbyists deal with three main types:
If you are a DIY mechanic, an automotive electrician, or a performance tuner working on a late-model Toyota, the number will appear repeatedly on the silver sticker of the Engine Control Unit (ECU). This seven-digit code is not a random part number; it is the first half of Toyota’s proprietary numbering system (89661-XXXXX), and it identifies a specific family of ECUs used across a massive range of vehicles—from the Corolla and Camry to the 4Runner, Land Cruiser Prado, and Hilux. toyota 89661 ecu pinout
or Engine Control Module (ECM). Because this part number is used across dozens of different Toyota and Lexus models from the 1980s to the 2020s, there is no single "proper" pinout that fits every unit. To find the correct wiring diagram, you must match the full five-digit suffix (e.g., 89661- ) and verify the specific engine code and production year. Identifying Your Pinout
To use the Toyota 89661 ECU pinout, you need to have a basic understanding of electronics and electrical systems. Here are some tips: | Pin | Wire Color | Function |
Never probe or depin an ECU with the battery connected.
Avoid using "test lights" on signal wires as they can draw too much current and fry internal ECU drivers. or Engine Control Module (ECM)
| Pin | Connector | Function | Voltage/Signal | |------|-----------|-------------------------------|----------------------| | A4 | A | ECU ground | 0V | | A10 | A | Glow plug relay control | 12V output (pre-heat) | | B11 | B | Common rail pressure sensor (PCR) | 0.5-4.5V | | B19 | B | SCV (Suction control valve) | PWM from 0-12V | | C3 | C | Fuel temperature sensor | 2V (at 40°C) | | C8 | C | Stop light switch input | 12V when braking |
Applying 12V to a 5V sensor reference pin (like B12 on many 89661 ECUs) will instantly destroy the analog-to-digital converter inside the CPU. Always triple-check your bench harness against the verified pinout.