Voices of the Void
The legendary MR2 Turbo ECU 89661-17320 (SW20 chassis) is a common platform for enthusiasts. Here is a simplified but direct pinout listing for the 3S-GTE ECU.
When modifying an 89661 harness, avoiding these common errors will prevent frying the computer:
Regardless of the specific model, certain pin labels remain consistent across the Toyota ecosystem: B+ / +B1 : Switched 12V power from the EFI relay.
Reversing this perspective will mirror your pin numbers and catastrophically wire your power leads into sensor inputs. Troubleshooting Common Wiring Issues toyota 89661 ecu pinout
If you are dealing with a rare JDM import or a modified harness, the safest way to verify pins is by opening the metal casing.
If you are a Toyota technician, a JDM engine swapper, or a DIY mechanic chasing an electrical gremlin, you have likely stumbled upon a silver box with the number stamped on the side. The Toyota 89661 series ECU (Engine Control Unit) is one of the most common engine computers found across a vast range of Toyota vehicles, from the legendary Land Cruiser and Hilux to the Corolla, Camry, and RAV4.
A signal wire that tells the ECU the ignition key has been turned to the "ON" position. 2. Ground Pins The legendary MR2 Turbo ECU 89661-17320 (SW20 chassis)
If the CEL doesn't illuminate when the key is in the "ON" position, the ECU is likely not receiving power (+B) or the internal capacitors have leaked. 6. Resources for Specific Diagrams
Constant 12V battery power directly from the fuse box (used to maintain ECU memory/trims).
Grounding this pin triggers diagnostic blink codes on older models. Voltage Feedback Used to read real-time oxygen sensor data and fuel trims. Step-by-Step Guide to Finding Your Specific 89661 Pinout Reversing this perspective will mirror your pin numbers
Ignition switch signal. Tells the ECU that the key has been turned to the "ON" position.
Note: Pin numbers are often stamped into the plastic behind the connector.
Permanent +12V battery power (used for keeping ECU memory/fault codes alive). IGSW: Ignition switch signal that tells the ECU to wake up. E1: Main chassis ground.
Multi-row, high-density configurations (often 4 or 5 blocks grouped together).
Do not assume pin positions by color coding. Toyota changes wire colors between model years and even between sedan vs. wagon versions of the same car.