Ultimate Toyota 89661 ECU Pinout Guide: Wire Your Engine Right
If you have an unknown ECU and no internet, you can map it yourself:
Wire color is a secondary identifier. Toyota uses "Lg-B" (Light Green-Black) for TPS on one car and "L-Y" (Blue-Yellow) for TPS on another. Always verify by pin position first.
: Distinctive yellow plastic connectors. Usually 2 to 4 large block plugs. Pins are counted sequentially across rows. The Gray/White Multi-Plug Era (Late 1990s – Mid 2000s) Common Engines : 2JZ-GTE (VVT-i), 1ZZ-FE, 2AZ-FE, 5VZ-FE. toyota 89661 ecu pinout
| | Pin # | Name / Label | Function | | :--- | :--- | :--- | :--- | | A | A20 | IGT – TACH + | Ignition Control Module (IGT) / Tachometer Signal | | A | A15 | G1 | Power Ground (for ECU's internal high-current drivers) | | B | B6 | OX | Oxygen Sensor (Primary O2 sensor signal) | | B | B4 | KNK | Knock Sensor (Signal used to detect engine knocking) | | B | B12 | IDL | Idle Switch (Part of TPS, signals closed throttle) | | B | B9 | E2 | Engine Sensor Ground (Ground reference for sensors) | | B | B11 | VTA | Throttle Position Sensor (TPS) Signal | | C | C2 | VS | Throttle Switch (Another TPS signal for load detection) | | C | C1 | VC | +5 Volt Sensor Power Supply (Vcc to TPS, MAP sensors) | | D | D4 | BRS | Brake Switch (Signal for ECU to know brake is applied) | | D | D9 | VSS | Vehicle Speed Sensor (Speed signal to ECU for idle, etc.) |
| | Pin | Symbol | Wire Color | Description | | :--- | :--- | :--- | :--- | :--- | | V Connector | 1 | VF | R-W | To Check Connector | | (Light grey) | 3 | STA | R-B | Neutral Start Switch (A/T) or Clutch Start Relay (M/T) | | | 5 | E01 | BR | Engine Ground (Power) | | | 6 | S/TH | G-R | Vacuum Switching Valve (VSV) | | | 7 | E1 | BR | Engine Ground | | | 8 | IGT | B | Signal to Igniter | | | 10 | E02 | BR | Engine Ground (Power) | | U Connector | 1 | NE | B-R | Engine Revolution Signal from Igniter | | (Blue) | 2 | THG | R-G | EGR Gas Temp. Sensor | | | 3 | G+ | W | Engine Revolution Sensor | | | 4 | G- | B | Engine Revolution Sensor Ground | | | 5 | IGF | B-Y | Igniter Confirmation Signal | | | 6 | IDL | L | Idle Switch from TPS | | | 7 | TEST | L-W | To Check Connector | | | 8 | W | R | Check Engine Lamp | | | 9 | FPU | LG | VSV for Fuel Pressure Up | | | 10 | THW | W | Coolant Temp. Sensor | | | 11 | VTA | R | Throttle Position Sensor | | | 12 | VCC | Y | +5V Sensor Power | | | 13 | OX | B | Oxygen Sensor Signal | | | 14 | E21 | BR | Sensor Ground | | | 15 | A/C | B-W | A/C Magnetic Clutch Signal | | | 17 | HT | R-B | Oxygen Sensor Heater | | | 18 | VISC | B | VSV (Idle Up) | | T Connector | 1 | +B1 | B-R | From Main EFI Relay | | (Brown) | 2 | BATT | R-W | Battery (+12V) | | | 3 | THA | B | Intake Air Temp. Sensor | | | 4 | VS | Y-L | Air Flow Meter Signal | | | 5 | VC | Y-B | Air Flow Meter Power | | | 8 | +B | B-R | From Main EFI Relay | | | 10 | SPD | V-W | Vehicle Speed Sensor | | | 11 | STP | G-W | Brake Switch Signal | | | 12 | E2 | BR | Sensor Ground |
Connect a fused 12V line straight from the battery to BATT . Ultimate Toyota 89661 ECU Pinout Guide: Wire Your
This article is a deep dive into the 89661 family of ECUs. We will cover what these numbers mean, why the pinout changes between models, how to identify your specific version, and provide a detailed breakdown of the most common connector configurations.
The pinout for the supercharged 4A-GZE engine (found in the AE101 Corolla) provides a good example of how a performance MAP (Manifold Absolute Pressure)-based ECU differs from the AFM (Air Flow Meter) design shown above. The 89661-12790 uses a 22-pin (Y), 26-pin (X), and 16-pin (Z) connector layout.
: Never ground a 5V sensor (like a TPS or MAP) to the car chassis. It must run back to the E2 pin on the ECU to avoid electrical interference and inaccurate sensor readings. : Distinctive yellow plastic connectors
If you are reading this, you likely have a Bosch-style Toyota ECU (Engine Control Unit) with the coveted part number prefix sitting on your workbench. Or, you might be staring at a tangled mess of wires under your dashboard after an engine swap. Either way, finding an accurate Toyota 89661 ECU pinout is your key to success.
Proper pinout documentation is critical for engine swaps. Many forums report successful swaps using 89661 ECU pinouts, including , where the owner found the VSS pin for speedometer to fix transmission shifting.