Toyota 89661 Ecu Pinout May 2026

| Pin | Typical Signal | Notes | |-----|----------------|-------| | A1 | IGT1 (Ignition timing signal 1) | To igniter | | A2 | IGT2 | | | A3 | IGT3 (if V6) | | | A4 | IGT4 (if V6) | | | A5 | IGF (Ignition confirmation) | From igniter | | A6 | NE+ (Crankshaft position sensor +) | Variable reluctance | | A7 | NE- (Crankshaft position sensor -) | | | A8 | G2+ (Camshaft position sensor) | | | A9 | G2- | | | A10 | THW (Engine coolant temp) | Analog input | | A11 | THA (Intake air temp) | Analog input | | A12 | VTA1 (Throttle position sensor) | Analog 0-5V | | A13 | VTA2 (TPS sub) | Redundant signal | | A14 | E2 (Sensor ground) | Common ground | | A15 | VC (Vref – 5V output) | To TPS, MAP, etc. | | A16 | KNK1 (Knock sensor 1) | | | A17 | KNK2 (Knock sensor 2) | V6 only | | A18 | OX1 (Front O2 sensor) | 0-1V or wideband | | A19 | OX2 (Rear O2 sensor) | | | A20 | STA (Starter signal input) | From ignition switch | | A21 | NSW (Neutral start switch) | Park/Neutral position | | A22 | SPD (Vehicle speed signal) | From speed sensor or ABS | | A23 | AC1 (A/C request) | | | A24 | ACMG (A/C magnetic clutch relay) | Output | | A25 | ELS (Electrical load signal) | Alternator load | | A26 | BATT (Battery backup) | Constant +12V for memory |

If you have the ECU but no diagram:

This is tedious but reliable for missing pinouts. toyota 89661 ecu pinout

Using a Digital Multimeter (DMM):

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 89661 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. | Pin | Typical Signal | Notes |

However, "89661" is not a universal pinout. It is a base part number prefix. While the physical plug shape may be similar across dozens of models, the pin assignments (which wire controls the fuel pump, which wire reads the crank sensor, etc.) change drastically based on the suffix letters (e.g., 89661-0D090 vs. 89661-2J170). This is tedious but reliable for missing pinouts

This article provides a deep-dive into the architecture of the 89661 ECU. We will cover how to identify your specific variant, decode the connector types, understand the common power and ground circuits, and provide strategies for finding the exact pinout for your application.